Secretary of State John Kerry said Sunday there was mounting evidence Russia assisted separatists in Ukraine in shooting down Malaysia Airlines Flight 17.
"We know for certain that in the last month there's been a major flow of personnel and weapons," including a convoy of 150 vehicles including 150 tanks and armored personnel carriers, Kerry said on CNN's State of the Union.
"At the moment of the shoot-down, we detected a launch from that area," Kerry said. "The trajectory went through that plane."
Asked whether Russia provided the weapon, Kerry told NBC's Meet the Press that the administration is unprepared to make that concrete assertion.
"We are not drawing the final conclusion here, but there's a lot (of evidence) to believe that Russia is responsible," he said.
Rep. Mike Rogers, chairman of the House Select Committee on Intelligence, said the missile system had Russian hands on it "at least at some point."
"This certainly eliminates (Russian President Vladimir) Putin's plausible deniability," Rogers said. "You're not going to hand this weapon off without having trainers present. The evidence is mounting this has at least Russian hands at some point on this missile system."
Also appearing on ABC's This Week on Sunday, Kerry said the missile fits the profile of a SA-11 because of the airliner's altitude. The SA-11 is a type of Russian-made anti-aircraft missile system.
On CNN, Kerry also said social media posts have provided a lot of information, including photographs of a BUK missile system in the area of the shoot-down, and a photo of such a system leaving the area with one missile missing.
A leader of the separatists' Donetsk People's Republic bragged on his website that rebels shot down a Ukrainian military transport in the moments after the shoot-down, and then removed the post after it became clear the flight was a civilian airliner, Kerry said.
"So it obviously points a very clear finger at the separatists," he said.
Kerry stopped short of saying Russia is responsible for the deaths of 298 crewmembers and passengers on the flight, but said the world, and European countries in particular, need to take stronger action against it.
"It would help enormously if some countries in Europe (that have not wanted to join sanctions) would get on board and step up," he said.
Kerry's comments come as anger mounts across the globe over the way the scene and the remains have been handled, with increasing calls for Putin to intervene.
"I am shocked by the images of utterly disrespectful behavior at the crash site — violating the rules of any investigation, there are people fooling around amid the debris, and picking through the personal and recognizable items of the victims," said Dutch Prime Minister Mark Rutte, whose country lost 193 people. "This is utterly disgusting."
Rutte said he had an "intense" conversation with Putin on Sunday morning and that he told Putin "time is running out" on his offer to help force the rebels in Ukraine to cooperate with the investigation.
After British Prime Minister David Cameron spoke with German Chancellor Angela Merkel about the issue Sunday, he tweeted that both agreed, "Putin must do more."
In an article for the Sunday Times, Cameron called the attack a "direct result of Russia destabilizing a sovereign state."