President Trump's decision to cut off aid to anti-government rebels in Syria marks a victory for President Bashar Assad in his six-year civil war — as well as allies Russia and Iran — and a defeat for U.S. efforts to remove the Syrian dictator.

Trump has decided to end a covert CIA program under President Barack Obama to train moderate rebels to fight Assad, The Washington Post reported Wednesday.

Report: Trump plans to end CIA training program for moderate Syrian rebels

The report comes two weeks after Trump met with Russian President Vladimir Putin in Germany and after the United States and Russia announced a limited cease-fire in southeastern Syria that promised to end Syrian airstrikes on rebel-held areas there.

Secretary of State Rex Tillerson said at the time that while the U.S. hopes to extend the truce to other parts of the country, U.S. policy remains that Assad and his family have "no long-term role" as rulers in Syria.

U.S., Russia reach deal on Syria cease-fire

The CIA training program was approved by Obama, who called for Assad to step down because of brutal oppression by his regime.

The U.S. government has accused Assad of bombing civilians and using banned chemical weapons. Trump ordered airstrikes against a Syrian military airfield in April following reports that Assad used chemical weapons against a rebel-held area that killed women and children.

The program was never big enough to accomplish the goal of Assad's ouster, said Frederic Hof, Obama's special Syria adviser who is now at the Atlantic Council think tank in Washington, D.C.

"If we’re if going to give this up we should get something in return because it is something of value,” he said. “It did some substantial good with specific (rebel) units and specific individuals, people we were trying to promote in terms of being non-sectarian alternatives to Assad.”

Iran provided troops and Russia, Assad’s other chief ally, provided the air force to support the Syrian government in September 2015, after U.S.-supplied rebels had scored a string of victories and threatened to overrun the Syrian capital, Damascus. Since then, Assad and forces supporting him have regained territory and vanquished rebel strongholds in Aleppo and Homs, two of the country’s largest cities.

McCain criticizes Trump's Syria policy despite cancer diagnosis

Senators Lindsey Graham, R-S.C., and John McCain, R-Ariz., both slammed Trump's Syria policy.

Graham wrote on Twitter Wednesday that Trump's move to end the CIA program, if true, “would be a complete capitulation to Assad, Russia, and Iran.”

It would be a loss for Syrians who have been relentlessly attacked by Assad, the U.S.’ Arab partners who’ve supported anti-Assad forces in Syria, and U.S. standing in the Middle East, Graham wrote.

“I fear this policy will lead to giving yet another Arab capital — Damascus — to the Iranians,” he said.

"If these reports are true, the administration is playing right into the hands of Vladimir Putin," McCain said in a statement Thursday. "Making any concession to Russia, absent a broader strategy for Syria, is irresponsible and short-sighted."

Putin launched his air war in Syria saying he would attack “terrorists,” but while the Islamic State committed multiple atrocities and Assad dropped barrel bombs on civilian targets, according to human rights groups, Russian airstrikes focused primarily on rebels fighting Assad.

The first targets of the Russian airstrikes were the CIA-trained units, Hof said, because Russia sought to “guarantee to the absolute possible that the opposition would be extreme sectarian and, somewhat, terrorists.”

The Putin-Assad strategy was to force the world to choose between Assad and extremists like al-Qaeda and the Islamic State, Hof said.

The CIA program had been plagued by problems that included red tape and poor supplies, and the Syrian fighters had a mixed record of success, he said.

“In southwest Syria, rebel forces trained, equipped and financed by the United States have done a pretty incredible job pacifying the area, fighting the regime and Iran-backed militias and also other extremists trying to get a foothold in the area,” he said. “In northwest Syria, they did a pretty good job, but al-Qaeda and other (extremist) groups dominated in the north.”

The focus of U.S. military action in Syria under Trump has been the Islamic State, which is based in Syria. U.S. special forces have trained a group of Kurds and Arabs to fight on the ground, supported by airstrikes by a U.S.-led coalition consisting of dozens of countries. That priority now is to retake the Syrian city of Raqqa, the Islamic State's de facto capital.

Andrew Tabler, a Syria analyst at the Washington Institute for Near East Policy, said there are still areas outside government control in Syria where the United States will want to maintain influence. And the CIA program may get folded into the military one, he said.

"If they just cut it off and don't replace it with something else, then yes" ending the CIA program would be a victory for Iran and Russia, Tabler said. "We'll have to wait and see what replaces it."