(CNN) - Russian President Vladimir Putin should "man up" and offer clear explanations amid important questions about the crash of Malaysia Airlines Flight 17, Senate Intelligence Committee Chairman Dianne Feinstein said on Sunday.
"I think the nexus between Russia and the separatists have been established very clearly. So the issue is, where is Putin?" Feinstein said in an interview on CNN's "State of the Union."
"I would say: 'Putin, you have to man up. You should talk to the world. You should say if this was a mistake, which I hope it was, say it.' Even if it was a mistake, it's a horrendous mistake to make," Feinstein added. "And I think it points out the futility of what's happening in the Ukraine. Because there will be repercussions from this."
The United States has said evidence suggests a Russian-made surface-to-air missile fired from the pro-Russia rebel territory took down the Malaysia Airlines Boeing 777 on Thursday. On board the plane were 298 people, with citizens from more than 10 nations. All of them were killed in the crash in eastern Ukraine.
"It's pretty clear that this is a system that was transferred from Russia in the hands of separatists," Secretary of State John Kerry told CNN on Sunday.
U.S. officials believe the missile systems may have been moved back across the border into Russia.
Russia has denied any involvement, and Putin said Ukraine's military campaign against the rebels was to blame. He also has called for a "thorough and objective investigation" of the crash.
Since the crash, the Ukrainian government and pro-Russian rebels have traded bitter accusations over who was responsible and what has been done since.
Ukrainian officials have said that a Russian-made Buk M1 missile system, brought into eastern Ukraine from Russia, had shot down the airliner.
But the local head of the rebels, Alexander Borodai, has rejected accusations that his forces shot down the plane, telling reporters that the rebels lacked the firepower to hit an aircraft that high.
During the interview, CNN's Candy Crowley pointed out previous sanctions against and meetings with Russia all designed to get that country out of the Ukraine and to stop supplying weapons to the separatists.
What makes anyone believe that Putin will "man up," Crowley asked Feinstein?
"I think the world has to rise up and say we've had enough of this," the senator said. "I think Europe has to come together. I think Germany, in particular, has to lead. I think we have to continue with sanctions. It's difficult, because you need Russian help in so many things."
CNN's Phil Black, Jethro Mullen and Ralph Ellis contributed to this report.