WASHINGTON (Reuters) - A senior Republican U.S. senator said he emerged from a White House meeting with President Donald Trump on Sunday reassured that Trump is committed to defeating Islamic State even as he plans to withdraw American troops from Syria.

Senator Lindsey Graham had warned that removing all 2,000 U.S. troops from Syria would hurt national security by allowing Islamic State to rebuild, betraying U.S.-backed Kurdish fighters of the YPG militia battling remnants of the militant group, and enhancing Iran’s ability to threaten Israel.

During a morning television interview, Graham said he would ask Trump to slow down the troop withdrawal, which was announced earlier this month and drew widespread criticism.

An ally of Trump, although he has opposed some of his foreign policy decisions, Graham was more upbeat after the meeting.

“We talked about Syria. He told me some things I didn’t know that made me feel a lot better about where we’re headed in Syria,” Graham, an influential voice on national security

policy who sits on the Senate Armed Services Committee, told reporters at the White House.

“We still have some differences but I will tell you that the president is thinking long and hard about Syria - how to withdraw our forces but at the same time achieve our national security interests,” Graham said.

Asked if Trump had agreed to any slowing down of the troop withdrawal, Graham said: “I think the president’s very committed to making sure that when we leave Syria, that ISIS is completely defeated.”

He said Trump’s trip to Iraq last week was an eye-opener and he understood the need to “finish the job” with Islamic State, also known as ISIS.

“I think the president has come up with a plan with his generals that makes sense to me,” Graham said.

Graham said later on Twitter that Trump would make sure that any withdrawal from Syria “will be done in a fashion to ensure: 1)ISIS is permanently destroyed 2)Iran doesn’t fill in the back end. And 3)our Kurdish allies are protected.”

The Pentagon says it is considering plans for a “deliberate and controlled withdrawal.” One option, according to a person familiar with the discussions, is for a 120-day pullout period.

U.S. Senator Lindsey Graham (R-SC) speaks to reporters after attending a closed-door briefing, on the death of the journalist Jamal Khashoggi, by Central Intelligence Agency (CIA) Director Gina Haspel at the U.S. Capitol in Washington, U.S., December 4, 2018. REUTERS/Jonathan Ernst

KURDISH FORCES

Graham told reporters that Trump was committed to making sure Turkey did not clash with the Kurdish YPG forces once U.S. troops leave Syria, and was assuring the NATO ally that it would have a buffer zone in the region to help protect its own interests.

Turkey views the YPG as a branch of its own Kurdish separatist movement and is threatening to launch an offensive against the group, igniting fears of significant civilian casualties.

U.S. commanders planning the U.S. withdrawal are recommending that YPG fighters battling Islamic State be allowed to keep U.S.-supplied weapons, according to U.S. officials.

That proposal would likely anger Turkey, where Trump’s national security adviser, John Bolton, holds talks this week.

Trump decided on the Syria withdrawal in a phone call with Turkish President Tayyip Erdogan, ignoring the advice of top national security aides and without consulting lawmakers or U.S. allies participating in anti-Islamic State operations. The decision prompted Defense Secretary Jim Mattis to resign.