Bairut, Lebanon. - Syria's military on Monday captured an enclave in southern Damascus from Islamic State militants following a ruinous monthlong battle, bringing the entire capital and its far-flung suburbs under full government control for the first time since the civil war began in 2011.
The gains freed President Bashar Assad's forces to move with allied militiamen on remaining rebel-held territory in the south near the border with Israel, as Syria's chief ally Iran comes under growing pressure from the Trump administration to withdraw its troops from the country.
Iranian-backed militias, including the Lebanese group Hezbollah, have been instrumental in helping Assad's over-stretched forces recapture huge areas around Damascus and in the country's center and north, building a military presence that has alarmed Israel and its U.S. ally, which is now looking to constrain Iran's activities.
Iranian officials have vowed to stay on in Syria for as long as needed, setting the stage for a potential confrontation as Washington seeks to tighten the screws on Tehran following the U.S. withdrawal from the 2015 Iran nuclear deal brokered with Iran under President Barack Obama and world powers.
U.S. Secretary of State Mike Pompeo threatened Iran with the "strongest sanctions in history" if Tehran doesn't change course. In his first major foreign policy speech since taking the post as the top U.S. diplomat, he issued a list of demands that he said should be included in any new nuclear treaty with Iran, including that it "withdraw all forces" from Syria, halt support for Hezbollah and stop threatening Israel.
Iran and Russia have joined forces in Syria, providing crucial military support to Assad's forces and giving them the upper hand in the civil war.
Russian President Vladimir Putin told Assad at a meeting last week that a political settlement in Syria should encourage foreign countries to withdraw their troops from Syria. Putin's envoy to Syria, Alexander Lavrentyev, said Putin was referring to Iranian forces, among others.
Iran says it is in Syria at the behest of the Assad government and says it is fighting "terrorism" in the form of Islamic extremists, including the Islamic State group and al-Qaida.
Iranian Foreign Ministry spokesman Bahram Ghasemi told reporters that no one can force Tehran to do anything it doesn't want to do.
"Our presence in Syria has been based on a request by the Syrian government and Iran will continue its support as long as the Syrian government wants," he said, speaking shortly before Pompeo made his remarks.
The recapture of IS-held pockets in the Palestinian refugee camp of Yarmouk and the nearby Hajar al-Aswad district in southern Damascus came after a massive bombing campaign that has all but decimated what was left of the residential area on the edge of the capital, once home to about 200,000 Palestinian refugees.