The Republican-led Senate voted 68-23 in favor of the amendment introduced by Senate Republican leader Mitch McConnell. It declares that the Islamic State's continued operations in both Syria and Afghanistan pose a threat to the United States.
Both the Islamic State and al-Qaida are recognized as "a global threat, which merits increased international contributions to the counterterrorism, diplomatic and stabilization efforts underway in Syria and Afghanistan," according to the amendment.
"Withdrawal of the United States forces from the ongoing fight against these groups ... could allow terrorists to regroup, destabilize critical regions, and create vacuums that could be filled by Iran or Russia, to the detriment of United States interests and those of our allies," it states.
McConnell said Thursday that his stance on the issue has been clear, as he was one of several Republicans who opposed the decision to withdraw about 2,000 service members from Syria when it was announced in December.
"I believe the threats remain. ISIS and al-Qaida have yet to be defeated, and American national security interests require continued commitment to our mission there," he said, using another name for the Islamic State.
Democrats who voted against the amendment described it as a commitment to endless war.
The amendment is part of a more expansive Middle East policy bill that has yet to pass the Senate and is likely to face a second vote there next week.
Nearly two weeks after announcing the Syria withdrawal plans, Sen. Lindsey Graham, R-S.C., said Trump had agreed to slow down the plans, adding the president had learned the Islamic State hadn't been "completely destroyed."