(CNN) ISIS' vandalism of one of Syria's most important historic sites looks set to escalate as Russian intelligence suggests that the militant group plans to wreak more destruction on the ancient Roman ruins at Palmyra.
The city has seen many of its irreplaceable antiquities, monuments and historic sites destroyed since the terror group first occupied it in May 2015.
Russia's Defense Ministry released a statement Monday saying they have detected "an upsurge in truck movement" near the ancient site that indicates that ISIS is planning to cause even more damage to the ancient complex.
"We have detected an upsurge in truck movement near the ancient city amid Syrian troops' successful advance on Palmyra," the statement reads. "This indicates that Daesh (ISIS) wants to bring in explosives to deal maximum damage to the remaining architectural relics before they leave."
Precious monuments lost in Middle East
Once the largest mosques in the world, built in the 9th century on the Tigris River north of Baghdad. The mosque is famous for the Malwiya Tower, a 52-meter minaret with spiraling ramps for worshipers to climb.
The site was bombed in 2005, in an insurgent attack on a NATO position, destroying the top of the minaret and surrounding walls.
Video: ISIS targets historical artifacts
An "oasis in the Syrian desert"
according to UNESCO, this Aramaic city has stood since the second millennium BC and featured some of the most advanced architecture of the period. The site subsequently evolved through Greco-Roman and Persian periods, providing unique historic insight into those cultures. ISIS now controls the ancient city and has
destroyed shrines, temples and monuments.
The most spectacular legacy of Buddhism in the war-torn country, among the tallest standing Buddhas in the world -- the larger at 53 meters, the other 35 -- had survived over 1,500 years since being carved out of sandstone. The Taliban considered the monuments idolatrous and
destroyed them with dynamite.
Yemen's capital city of Sanaa has seen several
suicide bombings for which ISIS claimed responsibility, and air strikes by the Saudi-led coalition -- although it is unclear who is responsible to the latest damage. These have affected both the old fortified city -- inscribed on UNESCO's
World Heritage List since 1986 -- and the archaeological site of the pre-Islamic walled city of Baraqish, causing "severe damage,"
according to UNESCO itself.
Continually inhabited for 2,500 years, and became the capital of the Romans' Arabian empire. The centerpiece is a magnificent Roman theater dating back to the second century that survived intact until the current conflict. Archaeologists have revealed the site is now severely
damaged from mortar shelling.
A world heritage site originally built in 715 by the Umayyad dynasty, ranking it among the oldest mosques in the world. The epic structure evolved through successive eras, gaining its famous minaret in the late 11th century. This was reduced to rubble in the Syrian civil war in 2013, along with serious damage to the walls and courtyard, which historians have described as the worst ever damage to Syrian heritage.
These 20-meter wide water wheels were first documented in the 5th century, representing an ingenious early irrigation system. Seventeen of the wooden norias (a machine for lifting water into an aqueduct) survived to present day and became Hama's primary tourist attraction, noted for their groaning sounds as they turned. Heritage experts
documented several wheels being burned by fighters in 2014.
The fortress spans at least four millennia, from the days of Alexander the Great, through Roman, Mongol, and Ottoman rule. The site has barely changed since the 16th century and is one of Syria's most popular World Heritage sites. The citadel has been used as an army base in recent fighting and several of its historic buildings
have been destroyed.
The covered markets in the Old City are a famous trade center for the region's finest produce, with dedicated sub-souks for fabrics, food, or accessories. The tunnels became the scene of fierce fighting and many of the oldest are
now damaged beyond recognition, which Unesco has
described as a tragedy.
This French-built suspension bridge was a popular pedestrian crossing and vantage point for its views of the Euphrates River. It became a key supply line in a battle for the city, and
collapsed under shelling. Deir Ez-zor's Siyasiyeh Bridge was also destroyed.
The
ancient Assyrian city around Nineveh Province, Iraq was home to countless treasures of the empire, including statues, monuments and jewels. Following the 2003 invasion the site
has been devastated by looting, with many of the stolen pieces finding homes in museums abroad.
The Crusader castle from the 11th century survived centuries of battles and natural disasters, becoming a World Heritage site in 2006 along with the adjacent castle of Qal'at Salah El-Din. The walls were severely damaged by
regime airstrikes and artillery in 2013, and rebels took positions within it.
The purported resting place of biblical prophet Jonah, along with a tooth believed to be from the whale that consumed him. The site dated to the 8th century BC, and was of great importance to Christian and Muslim faiths. It was
entirely blown up by ISIS militants in 2014 as part of their campaign against perceived apostasy.
Among Syria's most famous Ottoman-style mosques, which also shows
Mamluk influence through its light and dark contrasts. The vast site became a hub of the battle for Homs, itself a front-line of the conflict. The sacred mausoleum has
been completely destroyed, and much of the interiors burned.
A key city for the Greeks and Romans, established in 630 BC. Famed as the basis for enduring myths and legends, such as that of the huntress heroine of the same name and bride of Apollo. The ruins were some of the best preserved from that period, but in the wake of Libya's revolution,
vast tracts have been bulldozed including its unique necropolis complex.
Home to one of the world's most impressive collections, with over 100,000 pieces that cover the entirety of Islamic history. The Cairo site was first built in 1881, the museum recently underwent an eight-year multi-million dollar renovation. Shortly after re-opening, a car bomb targeting a nearby police building
caused catastrophic damage and forced the museum to close again.
This 121-year-old wooden building, humble but elegant, was home to the nation's first governor general Muhammed Ali Jinnah for the last phase of his life. The residency
was attacked with rocket fire by a separatist group in 2013, and almost completely demolished. A new structure is being built on the site.
A 15-year civil war of incredible brutality, successive battles with Israel, and sweeping urban development has robbed the 'Paris of the Middle East' of much of its visual lustre. Once known for its landscape of swaggering Ottoman, French and Art Deco architecture, officials say just 400 of 1200 protected historic buildings remain.
Before-and-after photographs of the destruction. The US and ISIS trade blame for
its loss.
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Footage shows wrecked sites
Footage from a Russian Unmanned Aerial Vehicle (UAV) shows the uptick in movement from ISIS' trucks in the region, showing "ISIS intentions to deliver explosives in order to cause maximum damage to the leaving architectural monuments before their retreat."
The same footage, the statement claims, also shows the destruction already wrought by the group, including the facade of the Roman theater and Tetrapylon column -- a square building erected in 270 AD -- along with the Triumphal Arch, Lion of Al-lāt, Temple of Baalshamin, Temple of Bel and other sites.
Russian topographers and archeologists from the Institute of Material Culture History at the Russian Academy of Sciences worked with the Defense Ministry to conduct a photo survey of the site, obtaining high definition 3D metric models of the terrain and architectural objects, which show greater detail than current satellite photos, the statement said.
"All this allows to imagine comprehensively and complexly what the ancient city used to be like before the barbarian(s') destruction," the statement added.
Is ISIS going broke?
Almost two years of destruction
ISIS fighters destroyed part of the historic Roman amphitheater in the ancient city in January after recapturing the historic city in December of last year. The amphitheater has also been used by the jihadist group for numerous executions.
In August 2015 ISIS also beheaded Khaled al-As'ad, a university professor and the former general manager for antiquities and museums in Palmyra. He had refused to reveal location of valuable antiquities to the militants.
The jihadist group first seized control of Palmyra, a UNESCO World Heritage Site, in May 2015. Syrian regime forces managed to briefly push the militants out of the city last year.
But Palmyra fell to ISIS again in December when Syrian troops pulled out and over 4,000 militants returned.
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CNN's Jomana Karadsheh, Kareem Khadder and Lauren Said-Moorhouse contributed to this report.