Moscow, Russia (BBN)-Russia has warned of the risk of a “proxy war” in the Middle East after the US said it would send special forces to Syria.
Russian Foreign Minister Sergei Lavrov said this increased the need for co-operation between the US and Russia, reports BBC.
US officials said “fewer than 50” troops would “train, advise and assist” vetted opposition forces in fighting the so-called Islamic State (IS).
It will be the first time that US troops operate openly in Syria.
Lavrov said the US had decided on its move “unilaterally and without any reference to the Syrian leadership”.
He added: “I am convinced that neither the United States nor Russia of course want any kind of slide into a so-called proxy war But to me it is obvious that this situation makes the task of co-operation between the militaries even more relevant.”
He was speaking after talks with US Secretary of State John Kerry and UN envoy for Syria Staffan de Mistura in Vienna.
“Our role fundamentally and the strategy is to enable local forces but does that put US forces in harm’s way? It does, no question about it,” Defence Secretary Ash Carter later told reporters.
He did not rule out further deployments of special forces to the region, if the initial mission was deemed a success.
For more than a year, US-led coalition forces have been carrying out air strikes against IS, which controls a large part of northern Syria and parts of neighbouring Iraq.
The US recently abandoned its Syria rebel training effort, opting to provide equipment and arms directly to rebel leaders instead.
White House spokesman Josh Earnest said President Obama wanted to provide additional support for Syrian rebel fighters who had been having success on the battlefield.
“There are now moderate opposition forces that are 45 miles (72km) outside [IS stronghold] Raqqa,” he said.
“The president is prepared to intensify the elements that have shown promise.”
He added: “This is an intensification of a strategy he discussed a year ago.”
US: Assad must go, but does not need to happen before a political transition process gets under way
Saudi Arabia: Assad must go “within a specific timeframe” and before any elections for a new government
Turkey: Assad must go, though could remain for a “symbolic” six months
SNC (main Western- and Gulf Arab-backed anti-Assad opposition): Assad must go, cannot be part of any political process
Russia: Assad should not be forced to go, Syrians should hold elections to decide who rules them
Iran: Assad should not step down, Syrians should decide their own political future
US special operations forces have previously taken part in at least two raids in Syria.
In May, troops killed senior IS member Abu Sayyaf and captured his wife in eastern Syria.
And last summer, forces failed in an operation to rescue American hostages including journalist James Foley, who was later beheaded by IS.
Last week, American forces assisted Kurdish troops in the rescue of dozens of hostages held by IS in Iraq. One American soldier was killed in the raid.