Iran said Monday that it had agreed to a deal to deepen military cooperation with Syria, reaffirming its intention to remain in the country despite moves by the U.S. and its allies to contain Tehran’s military reach.

Iran and Syria reached the deal following meetings Sunday between their defense ministers and Syria’s President Bashar al-Assad, according to Iran’s semiofficial Tasnim News Agency. The report offered no further details. Syrian state-linked media said the two sides reaffirmed the need the develop long-term cooperation, but made no mention of a new deal.

Iran has sent thousands of its own and allied forces to Syria to fight alongside Mr. Assad’s troops, and has also supported the Syrian regime with weaponry and oil.

The move to further cement the partnership comes as the Trump administration and Israel amplify calls for Iran to withdraw completely from Syria. Beating back Tehran has been a central goal of U.S. foreign policy under President Trump, who withdrew the U.S. in May from the Iran nuclear deal and has started reimposing sanctions that had been lifted under the Obama-era pact.

Iranian forces have been involved in Syria’s civil war since 2013, coming to the aid of Mr. Assad as he fended off a challenge from rebel groups and Islamic State extremists. Russia intervened to support Mr. Assad in 2015, helping him gain the upper hand in the conflict, which has now stretched more than seven years.