Seoul, South Korea(CNN) North Korea fired two ballistic missiles Wednesday morning -- including one into the Sea of Japan -- in the country's latest defiance of U.N. Security Council resolutions, U.S. and South Korean authorities said.
The missiles, presumed to be No Dong, or Rodong, intermediate range ballistic ones, were fired simultaneously from the country's west, the U.S. Strategic Command said.
One exploded after launch, the Strategic Command said. The other flew about 621 miles (1,000 kilometers) over North Korea and into the Sea of Japan, the South Korean Joint Chiefs of Staff said.
The firing drew international condemnation. Japan said the farthest-flying missile landed about 155 miles (250 kilometers) west of the Oga Peninsula inside its exclusive economic zone -- an area of the sea where a country claims maritime rights to resources such as fish, oil and gas.
Japanese Prime Minister Shinzo Abe called the launches a "serious threat."
"(That it) landed in our nation's EEZ makes it an intolerable act of recklessness," Abe said.
North Korea is prohibited from carrying out ballistic missile launches under U.N. Security Council resolutions aimed in part at curbing the country's development of nuclear weapons.
The launches "only serve to increase the international community's resolve to counter (North Korea's) prohibited activities, including through implementing existing U.N. Security Council sanctions," said Anna Richey-Allen, a spokeswoman for the U.S. State Department's Bureau of East Asian and Pacific Affairs.
A South Korean Defense Ministry official said that North Korea, "by firing of ballistic missile which can equip a nuclear warhead, is openly showing its direct and obvious intention of provocation and ambition that it can target our country, including our ports and airports, as well as neighbor countries."
On July 19, North Korea fired three ballistic missiles off its eastern coast.
Those were believed to be short-range, Scud or Rodong-type missiles and flew 300 to 380 miles (500 to 600 kilometers), said Jeon Ha-gyu, spokesman for the South Korean Joint Chiefs of Staff.
North Korean state media said Kim Jong Un, the country's leader, personally "provided field guidance" for that drill.
Missile tests have become more frequent under Kim's reign. The more tests the reclusive nation carries out, the more it can fix its mistakes, refining and improving its missile technology, experts say.
The South Korean defense official said North Korea has launched more than 30 missiles since Kim took power in 2011.
Though the country has continued to improve its nuclear and missile capabilities, it has yet to pair the two successfully.
Still, nations have moved to punish North Korea for developments in both areas. After the country tested a hydrogen bomb in January and launched a satellite with a long-range rocket in February, the Security Council imposed a round of sanctions in March.
Those included banning Pyongyang from exporting most of its natural resources, prohibiting the supply of aviation fuel and the sale of small arms to North Korea, and requiring the inspection of all North Korean planes and ships carrying cargo abroad.
Last month, South Korea announced it will deploy the advanced U.S Terminal High Altitude Air Defense missile defense system in Seongju County, about 155 miles (250 kilometers) southeast of Seoul.
When active, the THAAD system should be able to defend two-thirds of South Korea from an attack by its northern neighbor.
North Korea's military viewed the THAAD deployment as a provocation and said the United States and South Korea would "suffer from the nightmare extreme uneasiness and terror" in response.