PALMYRA, Syria, June 21 (UPI) -- Islamic State militants are planting explosive devices in the ancient Syrian ruins of Palmyra, according to a human rights monitoring group.
IS forces are now planting improvised explosive devices and landmines within the ruins as Syrian soldiers in the area have been bolstered with reinforcements, according to the Syrian Observatory for Human Rights.
The Britain-based monitoring group says "it is unknown whether they have mined the city in order to destroy the antiquities or to prevent the regime forces from [advancing] toward the city."
The BBC quoted SOHR director Rami Abdel Rahman as saying the Syrian military reinforcements suggest "they may be planning an operation" to recapture the ruins.
The IS capture of Palmyra stoked anxiety the ruins would be destroyed as other ancient sites had under the charge of "idolatry," including the dismantling and bulldozing of archeological sites in the northern Iraqi cities of Nimrud and Mosul earlier this year. Officials say the group also sells artifacts on the black market to fund operations.
In a strategic position on the road between Deir al-Zour, the city of Homs and Syria's capital, Damascus, Palmyra lies near gas fields and a major airbase.
On Sunday SOHR reported casualties on all sides in clashes between IS militants and Syrian regime forces, including allied militiamen, in the eastern countryside of Homs province.
Despite IS gains in Homs, the Sunni extremist group recently suffered setbacks against Kurdish YPG forces in the countryside north of Raqqa, the de facto IS capital. Last week the Kurds seized the northern border town of Tell Abiad, cutting off a major IS supply point for weapons and foreign fighters flowing in from Turkey.
Meanwhile, IS fighters last month sent Iraqi soldiers, police and allied militia retreating from the city of Ramadi in Iraq's Anbar province. Following the defeat, the Baghdad government activated Iran-trained Shia militias, and the administration of U.S. President Barack Obama deployed 450 more American troops to Iraq, bringing the total number beyond 3,500.
Both sides are preparing for an anticipated counter-attack, with intelligence sources suggesting IS forces are building a defensive network of IEDs and trenches.