MOSCOW -- Russia's upper house of parliament has voted unanimously to grant President Vladimir Putin the right to use the country's armed forces in Syria, where Moscow has sent warplanes and military equipment in a buildup that has raised questions about its intentions.
Putin's chief of staff, Sergei Ivanov, said the objective of the vote was to authorize the use of the Russian Air Force alone and that "the use of armed forces in a ground operation is ruled out."
"The military goal of this operation is exclusively to provide air support to the Syrian government forces in their fight against ISIS," Ivanov said in a televised statement, in a reference to Islamic State (IS) militants.
Ivanov spoke after the Federation Council voted 162-0 with no abstentions to approve Putin's request at a closed vote unexpectedly announced by upper house speaker Valentina Matviyenko on September 30.
Russia has for weeks been building up its military presence in Syria, where it has supported President Bashar al-Assad in a more than four-year civil war. Government forces are fighting against IS militants, other Islamic extremists, and rebel groups that in some cases are Western-backed.
Ivanov said the "most important" driver in the decision to step up Russia's involvement was the number of Russians and citizens of other ex-Soviet states joining IS, which he said was "growing by the hour," and the security threat they pose when they return.
He said "we are talking not of tens, not of hundreds, but of thousands of these Russians."
"It is advisable to act in advance and in the distant abroad rather than confronting the problem later at home in Russia. This is the most important. This decision is founded on these national interests," he said.
Ivanov said Putin asked the Federation Council to hold the vote after he received a formal request for military support from Assad. In Syria, Assad's office confirmed that this was the case.
"The Russian air force was dispatched to Syria after a request from the Syrian state via a letter by President Assad to President Putin that includes an invitation to send the Russian air force as part of President Putin's initiative to fight terrorism," the Syrian president's office said in a statement.
Ivanov said this request means that Russia's use of its armed forces in Syria does not contravene international law -- in contrast, he asserted, to air strikes by countries such as the United States, France, and Australia whom he singled out.
Russia has repeatedly said that the U.S.-led coalition conducting air strikes in Syria is acting illegally because it does not have the consent of Assad's government.
The United States and other Western governments suspect Russia's operations in Syria are aimed to protect Assad's government, not combat IS militants, and that its targets could include Western-backed rebels.
Putin and U.S. President Barack Obama clashed over Syria in speeches at the UN General Assembly on September 28, with Obama saying that Washington is willing to work with Russia to bring an end to the conflict in Syria but that any resolution to the war must include a "managed transition" away from Assad.
Putin called it "an enormous mistake to refuse to cooperate" with Assad's government to combat IS militants.
In an interview with CNN, U.S. Secretary of State John Kerry said that Russia's increased involvement in Syria could place Moscow in a "complicated" situation, suggesting it could prompt Putin to rethink his support for Assad.
"If he's going to side with Assad and with Iran and Hezbollah, he's going to have a very serious problem with the Sunni countries in the region [and could make Russia a target for Sunni extremists]," Kerry said.
"It's an opportunity for us to force this question of how you actually resolve the question of Syria," he added. "And the bottom line is, you cannot resolve it without including the Sunni[s] in a political solution, a political agreement ultimately, and that will mean that you're going to have to have some kind of transition, some kind of timing.Because as long as Assad is there, you simply can't make peace. Period."
Some media reports from the Middle East say Russian military jets have already carried out air strikes in Syria. The Kremlin has not confirmed those reports.
Ivanov declined to specify which weapons systems would be used in the air strikes.
Under Russian law, the consent of the upper parliament house is required for the deployment of the military abroad. The last time it was granted, in 2014, Moscow used troops to secure control of Crimea as part of its operation to annex the Black Sea peninsula from Ukraine.
With reporting by Reuters, AP, AFP, MSNBC, and CNN