"The U.S. government has grown strangely quiet on the accusation that it was Russia or her allies that brought down the Malaysian airliner with a Buk anti-aircraft missile," Paul said on his news website Thursday. 

U.S. officials believe the plane was brought down by a missile likely fired by pro-Russian separatists in Ukraine, killing all 298 people on board. The U.S. and Europe have slapped tougher sanctions on Moscow for providing the rebels with weaponry and assistance.

Paul, though, questioned that account and said the U.S. could be more forthcoming with information.

"It's hard to believe that the U.S., with all of its spy satellites available for monitoring everything in Ukraine, that precise proof of who did what and when is not available," the former lawmaker and GOP presidential contender said.