Russia on Friday condemned a US diplomatic cable calling for military strikes against the Syrian government, as Washington again accused Moscow of bombing US-backed rebels in the war-torn country.
Russian officials criticised the so-called "dissent channel" cable signed by a group of US diplomats urging strikes against Bashar al-Assad's regime, which it accuses of persistently violating a shaky ceasefire.
Kremlin spokesman Dmitry Peskov warned that attempts to overthrow Assad would not "contribute to a successful fight against terrorism".
"This could plunge the region into complete chaos," Peskov said.
Deputy foreign minister Mikhail Bogdanov said that attacks against the Syrian regime would be "at odds with (UN) resolutions".
"We need to negotiate and reach a political resolution on the basis of international law, which was agreed upon at the UN Security Council," Interfax news agency quoted Bogdanov as saying.
The cable calls for "a judicious use of stand-off and air weapons", according to the New York Times, laying bare stark divisions in Washington policy circles on the Syrian conflict.
Russian defence ministry spokesman Igor Konashenkov said in a statement that the US diplomatic cable could "not but cause concern to any sane person".
Moscow in September launched a bombing campaign in Syria to support long-time ally Assad, and the West has accused Russian forces of targeting the opposition with air strikes in an effort to prop up the regime.
A US official in Washington, requesting anonymity, on Thursday accused Russia of bombing US-backed fighters in southern Syria.
The Russian defence ministry said in a statement late Thursday that it carried out no air strikes on groups that had cooperated with Russia or the United States in the previous 24 hours.
Washington and Moscow have publicly vowed to work together to persuade Assad to negotiate a settlement with his opponents, but the US has frequently expressed exasperation about what it sees as Russia's less than full commitment.