Russia is playing a destabilizing role in Syria and acting as "both arsonist and firefighter" in the country, the head of U.S. Central Command said on Tuesday.

"Diplomatically and militarily, Moscow plays both arsonist and firefighter, fueling tensions among all parties in Syria... then serving as an arbitrator, to resolve disputes, attempting to undermine and weaken each party's bargaining positions," U.S. Army General Joseph Votel said during a House of Representatives Armed Services Committee hearing. He said Moscow is pushing alternatives to Western-led political negotiations in both Syria and Afghanistan in order to limit U.S. influence.

"Russia has placed this progress [vs. Daesh] at risk with its activities, which are not focused on defeating [Daesh] but rather on preserving its own influence and control over the outcome," he said, adding that Russia's interests in Syria were its own interests only, and "not of the wider international community."

Russia "has to admit" that it is incapable of, or not interested in, playing a constructive role in ending the multi-dimensional war in Syria, he said.

"I think their role is incredibly destabilizing at this point," he said.

For its part, the Russian military has consistently accused the U.S. of sparing Daesh and other militants in Syria in the hope of using them to topple Bashar Assad. Russian officials have strongly denied responsibility for any civilian casualties in Syria and insisted that they have only struck militant targets after verifying their location through multiple intelligence sources and avoided targeting populated areas. Russian military officials and diplomats also have scolded the U.S.-led coalition for reducing the one-time Daesh capital, Raqqa, to rubble and causing severe suffering for its residents.

On the military front in Syria, Votel said Russia is using the conflict to test and exercise new weapons and tactics, "often with little regard for collateral damage or civilian casualties." He asserted that an increase in Russian surface-to-air missile systems in the Middle East "threatens our access and ability to dominate the airspace" of the region.

He also said that along with Iran, Russia is trying to bolster the Syrian regime under Bashar Assad and fracture the longstanding strategic partnership between the United States and Turkey. Washington and Ankara are increasingly at odds over the presence of U.S.-backed People's Protection Units' (YPG), regarded by Turkey, as well as several U.S. intelligence entities, as the Syrian affiliate of the internaitionally-designated terorr group the PKK..

Alluding to these fighters, who operate under the banner of the Syrian Democratic Forces, Votel said, "our partners on the ground in Syria have advanced us a long way toward our objectives, and we will stick with them through the completion of this fight," referring to the goal of eliminating the Daesh's shrinking hold on Syrian territory.

Russian officials say they seek the destruction of Daesh even as they support Assad's effort to stamp out opposition forces. Votel said Moscow should get no credit for what he called the imminent defeat of the Daesh's "physical caliphate."

"Russia has placed this progress at risk with their activities, which are not focused on defeating [Daesh], but rather on preserving their own influence and control over the outcome of the situation," he said. "It is clear that Russia's interests in Syria are ... not those of the wider international community."

Votel said Moscow also is exaggerating the presence of Daesh fighters in Afghanistan and portraying it as a U.S. and NATO failure.

"While the (U.S.-led) coalition and the Afghans are the only forces actively fighting [Daesh] there, Russia has used familiar propaganda techniques to brand Daesh's presence as a U.S.-NATO failure," Votel said.

As Daesh loses its grip in Syria and Iraq, U.S. forces are turning increasingly to the battle in Afghanistan, where American commanders are trying to energize Afghan combat forces and break a stalemate in the long fight against a Taliban insurgency.

"Military success in the campaign up to this point presents us an opportunity to reposition some of our resources from Iraq and Syria to Afghanistan in a manner that keeps the pressure on ISIS, but also sets us up to break the stalemate in Afghanistan," Votel said.

U.S. forces have been in Afghanistan since October 2001, when they invaded in response to the 9/11 attacks by al-Qaida.

Votel also expressed concern about Iranian influence in Syria and Iraq, while noting that Iranian harassment of U.S. Navy vessels in the Persian Gulf has declined. Votel said he nonetheless is concerned by Iran's increasing used of drone aircraft, which he said pose a potential threat in the Gulf.