U.S. Defense Secretary Robert Gates is making his final trip to Russia as a cabinet member this weekend, as the two military powers struggle to find common ground in the campaign to put a missile-defense shield in Europe.

Gates trip comes just days after Moscow helped open the door for military action in Libya by not blocking the UN Security Council resolution supporting the move. Defense officials say it reflects a broader spirit of cooperation between the nations.

The travel will take Gates away from Washington just as the U.S. and its allies threaten a military attack on Libya if Moammar Gadhafi does not halt his brutal assault on civilians rebelling against the government. The U.S. is expected to provide strategic support if allies enforce a no-fly zone, The Associated Press reports.