(CNN) April 1975. The dog-end of the Vietnam War.
The South Vietnamese were demoralized after the U.S. withdrawal of combat forces in 1973 and the cessation of military support. The North Vietnamese, who had been fighting for nearly 20 years to see their homeland united under communism, seized the opportunity, launching a massive offensive.
Saigon, the South Vietnamese capital, fell, forcing the U.S. to stage a massive helicopter evacuation -- generating one of the best known images of the war.
The city was renamed Ho Chi Minh City, after the revolutionary leader, and the country was united and renamed the Socialist Republic of Vietnam (SRV).
The following years were fraught with ideological battles, famine and hostilities with China.
But fast-forward to today, and Vietnam has become what some commentators have called the Germany of Southeast Asia, its dedicated workforce and export-based economy have created an economic boom.
And there is a friendship forming with its old enemy.
Unthinkable scenes
On Sunday, President Obama will begin an official visit to Vietnam before continuing on to Japan.
His visit comes nearly a year after Vietnamese leader, General Secretary Nguyen Phu Trong, was welcomed to the White House.
Such scenes would have been unthinkable in the post-war years. Vietnam had banned citizens from leaving and began efforts to unify the country under a communist ideology.
"Bureaucrats, teachers, and civil servants from the defeated Republic of Vietnam underwent quick courses in re-education," says Christopher Goscha, author of the upcoming book, "A Modern History of Vietnam."
"However, those who were in the government, security services, and army found themselves doing time in re-education camps. Hundreds perhaps thousands spent years in detention."
Panicked by these developments, southerners crammed themselves into boats and fled: more than 755,000, according to the UNHCR.
The exodus continued as food shortages began to bite.
The Mekong Delta, in southern Vietnam, was home to the best rice fields. But the farmers there were resentful of the new regime and resisted attempts to increase yields.
Even if the southern farmers were amenable, the country's economic five-year plan was wildly ambitious, expecting to grow national income by 14%.
The plan failed. And by 1979 the government had to ration food. Citizens received a mere two kilograms of rice and 200 grams of meat per month.
War with China
Long-running tensions with giant neighbor China erupted following Vietnam's toppling of the Chinese-backed Khmer Rouge regime in Cambodia in 1978/9. Deng Xiaoping vowed to "teach Vietnam a lesson."
Within a month the war was over and, according to the Chinese, the lesson taught.
But the Vietnamese also claimed victory, saying they had beaten back their giant northern neighbor. Either way, the conflict helped to sour relations between China and the USSR, which was an ally of Vietnam.
Even though the USSR didn't come to Vietnam's aid in the war, they continued to be the prime funder of the SRV and even created a joint space program.
In 1980, Pham Tuan, a lieutenant colonel in the Vietnam People's Airforce, joined the Soviet Intercosmos program and became the first Asian in space.
As Tuan orbited the Earth, Vietnam's economy began to turn.
The Doi Moi reform program of the mid-1980s abolished the state-planned economy in favor of a "socialist-orientated market economy," similar to China. A new five-year plan called for a 70% increase in exports.
Iconic photos of the Vietnam War
1960s photojournalists showed the world some of the most dramatic moments of the Vietnam War through their camera lenses. LIFE magazine's Larry Burrows photographed wounded Marine Gunnery Sgt. Jeremiah Purdie, center, reaching toward a stricken soldier after a firefight south of the Demilitarized Zone in Vietnam in 1966. Commonly known as
Reaching Out, Burrows shows us tenderness and terror all in one frame. According to LIFE, the magazine did not publish the picture until five years later to commemorate Burrows, who was killed with AP photographer Henri Huet and three other photographers in Laos.
Associated Press photographer Nick Ut photographed terrified children running from the site of a Vietnam napalm attack in 1972. A South Vietnamese plane accidentally dropped napalm on its own troops and civilians. Nine-year-old Kim Phuc, center, ripped off her burning clothes while she ran. The image communicated the horrors of the war and contributed to growing U.S. anti-war sentiment. After taking the photograph, Ut took the children to a Saigon hospital.
Eddie Adams photographed South Vietnamese police chief Gen. Nguyen Ngoc Loan killing Viet Cong suspect Nguyen Van Lem in Saigon in 1968. Adams later regretted the impact of the Pulitzer Prize-winning image, apologizing to Gen. Nguyen and his family. "I'm not saying what he did was right,"
Adams wrote in Time magazine, "but you have to put yourself in his position."
A helicopter raises the body of an American paratrooper killed in action in the jungle near the Cambodian border in 1966. Henri Huet, a French war photographer covering the war for the Associated Press, captured some of the most influential images of the war. Huet died along with LIFE photographer Larry Burrows and three other photographers when their helicopter was shot down over Laos in 1971.
Legendary Welsh war photographer Philip Jones Griffiths captured the battle for Saigon in 1968. U.S. policy in Vietnam was based on the premise that peasants driven into the towns and cities by the carpet-bombing of the countryside would be safe. Furthermore, removed from their traditional value system, they could be prepared for imposition of consumerism. This "restructuring" of society suffered a setback when, in 1968, death rained down on the urban enclaves. In 1971 Griffiths published "Vietnam Inc." and it became one of the most sought after photography books.
Newly freed U.S. prisoner of war Air Force Lt. Col. Robert L. Stirm is greeted by his family at Travis Air Force Base in Fairfield, California, in 1973. This Pulitzer Prize-winning photograph, named Burst of Joy, was taken by Associated Press photographer Sal Veder. "You could feel the energy and the raw emotion in the air,"
Veder told Smithsonian Magazine in 2005.
This 1965 photo by Horst Faas shows U.S. helicopters protecting South Vietnamese troops northwest of Saigon. As the Associated Press chief photographer for Southeast Asia from 1962-1974, Faas earned two Pulitzer Prizes.
Oliver Noonan, a former photographer with the Boston Globe, captured this image of American soldiers listening to a radio broadcast in Vietnam in 1966. Noonan took leave from Boston to work in Vietnam for the Associated Press. He died when his helicopter was shot down near Da Nang in August 1969.
In June 1963, photographer Malcolm Browne showed the world a shocking display of protest. A Buddhist monk named Thich Quang Duc burned himself to death on a street in Saigon to protest alleged persecution of Buddhists by the South Vietnamese government. The image won Browne the World Press Photo of the Year.
Tim Page photographed a U.S. helicopter taking off from a clearing near Du Co SF camp in Vietnam in 1965. Wounded soldiers crouch in the dust of the departing helicopter. The military convoy was on its way to relieve the camp when it was ambushed.
Frenchman Marc Riboud captured one of the most well-known anti-war images in 1967. Jan Rose Kasmir confronts National Guard troops outside the Pentagon during a protest march. The photo helped turn public opinion against the war. "She was just talking, trying to catch the eye of the soldiers, maybe try to have a dialogue with them,"
recalled Riboud in the April 2004 Smithsonian magazine, "I had the feeling the soldiers were more afraid of her than she was of the bayonets."
In this 1965 Henri Huet photograph, Chaplain John McNamara administers last rites to photographer Dickey Chapelle in South Vietnam. Chapelle was covering a U.S. Marine unit near Chu Lai for the National Observer when a mine seriously wounded her and four Marines. Chappelle died en route to a hospital, the first American woman correspondent ever killed in action.
Mary Ann Vecchio screams as she kneels over Jeffrey Miller's body during the deadly anti-war demonstration at Kent State University in 1970. Student photographer John Filo captured the Pulitzer Prize-winning image after Ohio National Guardsmen fired into a crowd of protesters, killing four students and wounding nine others. An editor manipulated a version of the image to remove the fence post above Vecchio's head, sparking controversy.
For his dramatic photographs of the Vietnam War, United Press International staff photographer David Hume Kennerly won the 1972 Pulitzer Prize for feature photography. This 1971 photo from Kennerly's award-winning portfolio shows an American GI, his weapon drawn, cautiously moving over a devastated hill near Firebase Gladiator.
Hubert Van Es, a Dutch photojournalist working at the offices of United Press International, took this photo on April 29, 1975, of a CIA employee helping evacuees onto an Air America helicopter. It became one of the best known images of the U.S. evacuation of Saigon. Van Es never received royalties for the UPI-owned photo. The rights are owned by Bill Gates through his company, Corbis.
Associated Press photographer Art Greenspon captured this photo of soldiers aiding wounded comrades. The first sergeant of A Company, 101st Airborne Division, guided a medevac helicopter through the jungle to retrieve casualties near Hue in April 1968.
New Vietnam?
It was the beginning of a new Vietnam.
The country would become what some have termed Asia's quiet economic success story.
Annual income has grown from around $100 in 1986 to $2640 today -- nearly double in urban areas.
In 1991, President George H.W. Bush implemented a "roadmap to normalization" easing the trade embargo that had been in place since the end of the war.
By 1994, American companies could enter the Vietnamese market and Vietnam could integrate with the global economy.
America opened a new embassy in Hanoi in 1995.
They also increased efforts to help clean up vast tracts of land poisoned by Agent Orange and committed to "clear up its brass" -- to use a military term -- and help dispose of unexploded remnants of war.
The Vietnam War
South Vietnamese troops wade through water to flush out communist rebels, known as the Viet Cong, in 1962. Several years earlier, North Vietnamese communists began helping the Viet Cong fight South Vietnamese troops. They wanted to overthrow the South Vietnamese government and reunite the country, which split in 1954.
On July 21, 1954, Vietnam signs the Geneva Accords and divides into two countries at the 17th parallel: the communist-led north and U.S.-supported south. Vietnam had been a part of the colonial empire French Indochina until communists in the north began fighting France for control of the country.
A man appears fearful as he is questioned by South Vietnamese soldiers in August 1962.
American planes drop napalm on Viet Cong positions in 1962. Hoping to stop the spread of communism in Southeast Asia, the U.S. also sent aid and military advisers to help the South Vietnamese government. The number of U.S. military advisers in Vietnam grew from 900 in 1960 to 11,000 in 1962.
U.S. troops in Vietnam salute the coffins of seven American soldiers who were killed in a helicopter crash circa 1963.
Thich Quang Duc, a Buddhist monk, burns himself to death on a street in Saigon -- the capital of South Vietnam -- on June 11, 1963. He lit himself on fire to protest alleged persecution of Buddhists by the South Vietnamese government.
A father holds the body of his child as South Vietnamese Army Rangers look down from their armored vehicle in March 1964. The child was killed as government forces pursued guerrillas into a village near the Cambodian border.
The U.S. Navy destroyer USS Maddox, seen here, was anchored in the Gulf of Tonkin when it was attacked by the North Vietnamese in August 1964. After U.S. President Lyndon Johnson falsely claimed that there had been a second attack on the destroyer, Congress passed the Gulf of Tonkin resolution, which authorized full-scale U.S. intervention in the Vietnam War. Johnson ordered the bombing of North Vietnam in retaliation for the Tonkin attack.
A South Vietnamese reconnaissance unit walks hip-deep in water as a U.S. helicopter skims over reeds in the Mekong Delta in October 1964. They were on the lookout for Viet Cong guerrillas.
Injured people receive medical aid after an explosion at the U.S. Embassy in Saigon on March 30, 1965.
A suspected Viet Cong is kicked by a South Vietnamese soldier in October 1965. The prisoner was one of 15 captured in a raid near Xom Chua.
Women and children crouch in a muddy canal as they take cover from intense Viet Cong fire at Bao Trai, about 20 miles west of Saigon, in January 1966.
Staff Sgt. Harrison Pell, a wounded American soldier, drinks from a comrade's canteen during a January 1966 firefight between U.S. troops and a combined North Vietnamese and Viet Cong force.
A Viet Cong soldier holds an anti-tank gun during the Tet Offensive, a massive surprise attack launched in 1968 by the North Vietnamese. The attack hit 36 major cities and towns in South Vietnam. Both sides suffered heavy casualties.
South Vietnamese Gen. Nguyen Ngoc Loan, chief of the National Police, fires his pistol into the head of suspected Viet Cong officer Nguyen Van Lem on a Saigon street on February 1, 1968, early in the Tet Offensive.
A young refugee carries an elderly woman on his back while crossing a bridge in Hue, Vietnam, in 1968.
Troops look at the aftermath of an attack on the U.S. Embassy in Saigon in 1968.
A U.S. Army first sergeant guides a medevac helicopter through the jungle to pick up casualties suffered near Hue in April 1968.
A South Vietnamese woman mourns over the body of her husband, which was found with 47 others in a mass grave near Hue in April 1969.
U.S. President Richard Nixon points to a map in the White House after telling the nation that American troops have attacked, at his order, a communist complex in Cambodia in April 1970. Nixon ordered troops to invade border areas in Cambodia and destroy supply centers set up by the North Vietnamese.
On May 4, 1970, National Guard units fired into a group of anti-war demonstrators at Kent State University in Ohio. The shots killed four students and wounded nine others. Anti-war demonstrations and riots occurred on hundreds of other campuses throughout May.
U.S. artillerymen relax under a crudely made peace flag at the Laotian border in 1971. In February 1971, U.S. and South Vietnamese troops invaded southern Laos in an effort to stop North Vietnamese supply routes. This action, ordered by President Nixon, was done without consent of Congress, and it led to more anti-war protests.
South Vietnamese forces follow after terrified children after a napalm attack on suspected Viet Cong hiding places in June 1972. A South Vietnamese plane accidentally dropped napalm on South Vietnamese troops and civilians. The terrified girl in the center had ripped off her burning clothes while fleeing.
North Vietnamese Foreign Minister Nouyen Duy Trinm signs a ceasefire agreement in Paris on January 27, 1973. The last American ground troops left in March of that year. Fighting would resume between North and South Vietnam, but the United States did not return.
Air Force Lt. Col. Robert L. Stirm, a released prisoner of war, is greeted by his family in Fairfield, California, as he returns home on March 17, 1973.
A cargo net lifts refugees from a barge so they can be evacuated from the city of Da Nang, Vietnam, on April 1, 1975.
Mobs of Vietnamese people scale the wall of the U.S. Embassy in Saigon on April 29, 1975, trying to get to a helicopter pickup zone. A day later, South Vietnam surrendered to North Vietnam when North Vietnamese troops entered Saigon. Saigon is now called Ho Chi Minh City in honor of the late North Vietnamese leader.
U.S. President Barack Obama stands at the Vietnam Veterans Memorial in Washington in May 2012. The black granite memorial bears the names of more than 58,000 Americans killed in the Vietnam War.
READ: Political intrigue and power struggles as Vietnam chooses new leader
Arms embargo to go?
Today, Vietnam is increasingly worried about the presence of Chinese military in the South China Sea. It wants to buy weapons from the U.S. but is prevented by a decades-old arms embargo.
But the U.S. has said that progress on human rights is important for a full lift of the ban.
Nguyen Tan Dung, the Vietnamese premier, may have some leverage in negotiations because Obama wants to maintain U.S. presence in the region in the face of increasing Chinese assertiveness, analysts say.
"Obama is keen to join Vietnam in containing the expansion of Chinese maritime power into the Pacific," says Goscha.
"His visit is a signal to Vietnam of the U.S. readiness to write a new page in American-Vietnamese relations, but it is also part of a wider strategy and series of relationship with other Asian countries worried by China's expansion."