Benchmark West Texas Intermediate crude for October delivery fell $1.01 to close at US$109.52 a barrel on the New York Mercantile Exchange. On Friday, oil gained $2.16 to close at US$110.53, the highest closing price since May 3, 2011.
President Barack Obama has called for military action against the government of Syrian President Bashar Assad in retaliation for what the White House says was a chemical weapons attack against civilians in suburban Damascus last month. But he has so far failed to win sufficient support for intervention both at home and abroad.
Obama plans an address from the White House on Tuesday about Syria.
On a Monday, there was hope for a possible diplomatic solution when Syria's foreign minister welcomed a suggestion floated by U.S. Secretary of State John Kerry to move all the country's chemical weapons under international control.
The White House said it was taking a hard look at Syria's statement even as it redoubled efforts to sell the notion of the strike to a skeptical Congress and divided nation and senators prepared for a key test vote on the strike authorization Wednesday.
Brent, the benchmark for international crudes, dropped $2.40, or 2.1 per cent, to US$113.72 a barrel on the ICE Futures exchange in London.
In other energy futures trading on Nymex, wholesale gasoline fell five cents to US$2.80 a U.S. gallon (3.79 litres), heating oil retreated five cents to US$3.12 a gallon and natural gas rose eight cents to US$3.61 per 1,000 cubic feet.
(TSX:ECA), (TSX:IMO), (TSX:SU), (TSX:HSE), (NYSE:BP), (NYSE:COP), (NYSE:XOM), (NYSE:CVX), (TSX:CNQ), (TSX:TLM), (TSX:COS.UN), (TSX:CVE)