According to U.S. officials briefed on the latest intelligence regarding the deadly attack on Malaysian Airlines Flight 17 now point to Russia as the source of the sophisticated weapon used to take that plane out of the sky on Thursday.

Speaking with both The Washington Post and The Wall Street Journal on Saturday, it is clear Washington now believes the SA-11 anti-aircraft missile used in the attack on MH17 was just one of the powerful weapons Moscow supplied pro-Russian militants in Ukraine with in recent weeks.

“U.S. officials say they now suspect that Russia supplied the rebels with multiple SA-11 antiaircraft systems by smuggling them into eastern Ukraine with other military equipment, including tanks,” read a report in The Journal.

The added certainty that the SA-11 systems likely were in rebel hands also poses questions about why Ukraine or U.S. officials didn’t move more quickly to advise commercial jetliners of potential dangers, if there was time after they learned of possible rebel control of the systems.

Moscow has continued to deny supplying armed separatists with heavy weapons, despite mounting evidence to the contrary put forward by U.S. officials. “We know there are Russian troops inside Ukraine,” said a U.S. official. “Russian troops, Russian equipment.”

The Post’s sources corroborated the claims made in The Journal:

“We do believe they were trying to move back into Russia at least three Buk [missile launch] systems,” the official said. U.S. intelligence was “starting to get indications . . . a little more than a week ago” that the Russian launchers had been moved into Ukraine, said the official.
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Two of the antiaircraft systems were spotted entering Russia from Ukraine at 2 a.m. Friday, he said. One had its full complement of four missiles, but the other was missing a missile, he said. Two hours later, he said, a convoy of three vehicles that included one of the launchers and a control truck crossed into Russia.

The crash site has already been compromised by the pro-Russian militants in control of the area. Bodies and aircraft debris, including the plane’s black boxes according to some reports, have already been removed by separatists loyal to Moscow. Many of the bodies of the victims are reportedly being left by rebel forces to rot in the summer heat.

The Post reported that the attack and the rebels’ treatment of the crash site are “hardening” attitudes toward Russia’s exacerbation of this conflict. The Netherlands, which lost 192 nationals in this attack, had been one of the European countries concerned about the prudence of imposing tougher sanctions on Moscow.

In a phone call with British Prime Minister David Cameron on Saturday, reported in The Journal, Dutch Prime Minister Mark Rutte reportedly said that he called on the European Union to “reconsider its approach to Russia in light of evidence that pro-Russian separatists brought down the plane.”