WASHINGTON — In presenting the most detailed case yet alleging Russia’s involvement in the Ukraine crisis, Secretary of State John Kerry said on Sunday that Russia had funneled large quantities of heavy weapons to Ukrainian separatists and trained them how to operate SA-11 antiaircraft missiles, the type of system that is believed to have been used to shoot down the Malaysian airliner over eastern Ukraine.

“We know for certain that the separatists have a proficiency that they’ve gained by training from Russians as to how to use these sophisticated SA-11 systems,” Mr. Kerry said on the CNN program “State of the Union.”

Appearing on five network news programs on Sunday, Mr. Kerry laid out a litany of findings that he said pointed to Russian involvement in support of the separatists who most likely shot down the airliner on Thursday, killing all 298 on board.

American officials have said in recent days that the SA-11 unit was believed to have been transported to Ukraine from Russia shortly before the plane was downed. And the American Embassy in Kiev released a statement saying audio of separatist leaders discussing the downed airliner, released by Ukraine’s security service, was authentic.