The crisis over Russia's threatening military buildup on the border with Ukraine entered a dangerous and unpredictable new phase in both Vienna and Washington on Thursday.
Driving the news: Russian diplomats said this week's round of security talks from Geneva and Brussels to Vienna have resulted in a "dead end," and it's time for them to return to Moscow to brief President Vladimir Putin on the "very disappointing" state of affairs before deciding the path forward.
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"It seems the risk of war in the OSCE area is now greater than ever before in the last 30 years," Zbigniew Rau, the Polish chairman of the Organization for Security and Cooperation in Europe, said at the outset of Thursday's meeting in Vienna.
Michael Carpenter, the U.S. ambassador to the OSCE, told reporters: "We're facing a crisis in European security. The drumbeat of war is sounding loud and the rhetoric has gotten rather shrill."
At the White House, national security adviser Jake Sullivan told reporters the intelligence community has information that Russia is "laying the groundwork" for a potential pretext to invade Ukraine, such as fabricating a provocation by Ukrainian forces.
Sullivan said the administration would share more details with the press over the next 24 hours.
On Capitol Hill, the Senate defeated a bill from Sen. Ted Cruz (R-Texas) to sanction the Putin-backed Nord Stream 2 pipeline. That followed an aggressive lobbying campaign by the Biden administration.
The Senate will now take up a Democratic-sponsored package that would trigger a cascade of crushing sanctions - including on Putin himself - if the Biden administration determines Russia has crossed a line on Ukraine.
Republicans will push to hold a vote on their own package, which would sanction Nord Stream 2 and provide security assistance to the Ukrainians now - rather than after an invasion.
Between the lines: At issue in the coming fight over sanctions is a fundamental foreign-policy question - is it sanctions that deter bad actors, or the threat of sanctions?
"As both the Ukrainians and many of us have been saying, if we want to send a signal of deterrence, we have to act now, not sit on our hands," a senior Republican aide told Axios.
Sen. Chris Murphy (D-Conn.) told reporters the U.S. needs to "make clear to Vladimir Putin that the relationship between the United States and Russia will be fundamentally different" if Russia invades Ukraine.
What they're saying: "A conventional invasion of Ukraine shatters post-World War II norms," Murphy said. "It needs to be treated as a serious, significant, world-shattering breach of international norms."