Russian Chief General Staff Gen. Valery Gerasimov has accused the United States of training former Daesh militants in Syria to try to destabilize the country.

Gerasimov's allegations, made in a newspaper interview, concern a U.S. military base in Tanf, a strategic Syrian highway border crossing with Iraq in the south of the country, as reported by Reuters. He claimed the U.S. base is illegal and that it and the area around it have become "a black hole" where militants operate unhindered.

Daesh has this year lost almost all the territory it held in Syria and Iraq. Russian Foreign Minister Sergei Lavrov said yesterday the main part of the fight against Daesh in Syria is over, according to the state-run RIA news agency.

The United States says the Tanf facility is a temporary base used to train partner forces to fight Daesh. It has rejected similar Russian allegations in the past, saying Washington remains committed to destroying Daesh and denying it safe havens.

But Gerasimov told the Komsomolskaya Pravda newspaper on Wednesday that the United States was training up fighters who were former Daesh militants but who now call themselves the New Syrian Army or use other names. He said Russian satellites and drones had spotted militant brigades at the U.S. base.

"They are in reality being trained there," Gerasimov claimed, saying there were also a large number of militants and former Daesh fighters at Shadadi, where he said there was also a U.S. base. "They are practically [Daesh]," he said. "But after they are worked with, they change their spots and take on another name. Their task is to destabilize the situation."

Russia has partially withdrawn from Syria, but Gerasimov said the fact that Moscow was keeping an air base and naval facility there means it is well placed to deal with pockets of instability if and when they arise. Russia's military presence in Syria was cut to three military police battalions and the Center for the Reconciliation of the Warring Sides, as reported by the Russian TASS news agency.

Russian President Vladimir Putin's brief stop at the Khmeimim Air Base in Syria's coastal province of Latakia came days after Russia announced the liberation of Syria from Daesh – a claim disputed by the Syrian Observatory for Human Rights. Khmeimim Air Base has served as the main foothold for the air campaign Russia has waged since September 2015 in support of the regime. Russia had previously announced a partial drawdown of its forces in Syria in March last year. However, a powerful Russian contingent remained in place and there is little sign of operations being scaled back.

Syria has been locked in a vicious civil war since 2011, when the Assad regime cracked down on pro-democracy protests with unexpected ferocity. Since then, hundreds of thousands of people have been killed in the conflict, according to the U.N.