The reported downing of a Malaysian airliner over eastern Ukraine that resulted in the deaths of 295 passengers was an “act of terror” and an “act of war,” according to the top Democrats on the House Foreign Affairs and Senate Armed Services Committee.

“The shooting down, if it’s true, of a passenger airliner is an act of terror,” New York Rep. Eliot Engel, the top Democrat on the House Foreign Affairs Committee, told The Daily Beast. “It’s no different from the acts of terror Iran has been perpetrating for many years… The world community should get together and decide on a solidified response.”

Engel said there was no doubt in his mind that Russian President Vladimir Putin was encouraging and supporting the Ukrainian separatists who stand accused of shooting down the Boeing 777, Flight MH17 from Amsterdam to Kuala Lampur. According to Engel, that means Putin could have at least indirect responsibility for this as well as the other incidents, including the downing of a Ukrainian military transport plane earlier this week.

The Obama administration yesterday announced expanded sanctions against Kremlin officials, Russian defense firms, Moscow’s financial institutions—as well as the so-called Donetsk People’s Republic and Luhansk People’s Republic, the two regions of eastern Ukraine that have declared independence from Kiev.

Engel and other lawmakers said Thursday that if Moscow-supported separatists did shoot down the plane, the administration should move forward with even more sanctions against Russia quickly.

“All the facts haven’t come out yet… I think what [Putin] is doing is very dangerous,” he said, referring to Putin’s overall meddling in Ukraine. “I would be for stronger sanctions if it’s proved that Putin had anything to do with this.”

Senate Armed Services Committee Chairman Carl Levin (D-MI) said Thursday that the perpetrators of the attack, even if it’s a foreign government, should be held accountable.

“Whoever did it should pay a full price,” he said. “If it’s by a country, either directly or indirectly, then it could be considered an act of war.”

National Security Council spokeswoman Bernadette Meehan declined to say whether the White House agrees with Engel that the downing of MH17 was an “act of terror.”

Sen. Mark Kirk (R-IL) said in a Thursday interview with The Daily Beast that if Americans were killed in the attack—and there are unconfirmed reports that there have been—their families should immediately pursue civil lawsuits against Russian interests in the U.S. and Europe. It’s a tactic employed in the wake of previous commercial airline attacks.

“If we’ve had American deaths here, there should be a pretty swift response against Russian assets which are located in North America… The Justice Department should assist the litigants,” he said. “The families of those Americans should immediately come forward with lawsuits that lock up a lot of Russian assets here in the U.S. and get recompense so the Russian oligarchs always know that it will hit them in their foreign pocketbooks if they needlessly kill civilians.”

The Ukrainian foreign ministry released a statement promising to present evidence of Russian involvement.

“According to the General Staff of Ukrainian Armed Forces, the airplane was shot down by the Russian Buk missile system as the liner was flying at an altitude of 10,000 meters [33,000 feet],” the statement said. “Ukraine has no long-range air defense missile systems in this area. The plane was shot down, because the Russian air defense systems was affording protection to Russian mercenaries and terrorists in this area.”

Kirk, a former Naval intelligence officer, said the Buk—also known as the SA-17 anti-aircraft weapons system—had been standard issue for Soviet Bloc countries, including Ukraine. But the real connection to Moscow is that they directly support the separatist militia.

“I don’t know who was the idiot who fired the shot… [but] you would worry that separatists that have been paid by Putin pulled the trigger. That gives some culpability against Russia,” he said.

Kirk compared the incident to the 1983 shoot-down of Korean Airlines Flight 007 by the Russian military, which killed 269 people, including Georgia Congressman Lawrence McDonald.

“It was a key turning point in the Cold War, where Russian just saw its reputation trashed and then was unable to get anything going in the international forum,” Kirk said. “

Sen. Lindsey Graham told reporters Thursday that the lawmakers would push for increased sanctions and increased support to the Ukrainian military in light of the plane tragedy.

“I don’t even need the airliner incident. I would go ahead and arm the Ukrainian military so that they could better defend themselves, and I would push the international community to get behind the new round of sanctions,” he said. “[Putin] doesn’t need to shoot down an airliner to be in my bad graces.”

Senior Obama administration officials told reporters Wednesday that Russia had consistently reneged on its promises to try to de-escalate the crisis in Eastern Ukraine and was directly arming the separatists with advanced weaponry.

“You will have seen on social media over the last week convoys of Russian tanks, armored personnel carriers, infantry combat vehicles, Grad rocket launchers, howitzers, self-propelled mortars flowing into Ukraine,” one official said. “So the concern has been that not only has Russia not availed itself of the diplomatic openings to deescalate, but the support for separatists has increased.”

— with additional reporting by Tim Mak