Rex Tillerson has announced that there is no place for Syrian President Bashar al-Assad in Syria’s future and vowed that the U.S. military will remain in the war torn country to counter ISIS, al-Qaeda and Iran

The US Secretary of State said that “diminishing” Iran’s influence in Syria is a key goal for U.S. policy in Syria while calling for closer cooperation with Russia to avoid conflict in “de-escalation zones.”

According to Bloomberg He also offered financial aid and diplomatic assistance to help rebuild areas shattered by almost seven years of civil war and said Assad’s eventual departure is inevitable.

“Responsible change may not come as immediately as some hope for, but rather through an incremental process of constitutional reform and UN-supervised elections,” Tillerson said in the prepared remarks for his speech at Stanford University’s Hoover Institution in California. “But change will come.”

The speech offered the clearest articulation of the Trump administration’s determination to maintain a U.S. presence in Syria, where Assad has managed to consolidate his grip after Russia’s military intervention on his behalf in 2015. According to a Pentagon estimate in December, the U.S. has about 2,000 troops in Syria as well as a diplomatic presence in cities such as Kobani. Despite that, Washington has seen discussions over Syria’s future overtaken by a Russian-led effort that has largely sidelined Western powers.

Contrary to the U.S. position, Russia has indicated Assad may stay in power and criticized the U.S. for seeking “regime change.” Moscow’s envoy to Syria last month said he saw no reason why Assad “shouldn’t or wouldn’t run for another presidential term.”

Nevertheless, Tillerson said the overarching goal for the U.S. is to make progress toward a vote in which Syrians at home and overseas would usher in a “post-Assad” government to rebuild.