In a step seen as a concession to Russia, Donald Trump has ended covert CIA assistance to Syria’s rebels.

Unnamed US officials said Trump decided to end the program almost a month ago after meeting with National Security Adviser H.R. McMaster and CIA Director Mike Pompeo.

That meeting came before Trump’s two bilateral discussions with Russian President Vladimir Putin at the G20 summit in Germany.

The officials said the program, which began in 2012, will be phased out over the course of months.

An unnamed current official said the halt to the program “is a momentous decision” constituting a victory for Russia: “Putin won in Syria.”

The Obama Administration had limited the CIA program in 2015, following rebel advances in both northwest and southern Syria. US officials were reportedly wary that the backing of the Southern Front, assisted by the Military Operations Center in Jordan, could lead to an offensive on Damascus and the sudden fall of Bashar al-Assad without a clear succession.

Russia’s military intervention, rescuing the Assad regime, came a few months later at the end of September 2015.

The US still provides weapons and special forces for the Free Syrian Army in eastern Syria, including at a base near the Iraqi border, on condition that the FSA fights the Islamic State and not pro-Assad forces.

Most of Washington’s support is now devoted to the Kurdish-led Syrian Democratic Forces as they try to defeat ISIS in northern Syria.