Washington (CNN)The serious escalation of fighting in Ukraine is pushing President Barack Obama closer to the proxy war with Russia that he has long sought to avoid. That prospect is increasing as the United States openly accuses its former Cold War foe of sending tanks and troops in unmarked uniforms across the border into eastern Ukraine, boosting separatists in their battle against Kiev's beleaguered forces. The revelations are sharpening Obama's dilemma as his White House considers whether to send "lethal" weapons, including anti-tank and anti-mortar systems to the outgunned Ukrainian armed forces. Obama's nominee to become the next Defense Secretary, Ashton Carter, bolstered that idea during his confirmation hearing on Wednesday.
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U.S. considering sending arms to Ukraine
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But critics fear move could escalate US-Russia showdown
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No one knows how Putin would respond
United States
U.S.
US
There is no guarantee that funneling sophisticated @placeholder armaments into the conflict could be decisive, and the gambit could antagonize Vladimir Putin, Russia's increasingly isolated and hard-to-read leader.
Russia
Russia
There is no guarantee that funneling sophisticated U.S. armaments into the conflict could be decisive, and the gambit could antagonize Vladimir Putin, @placeholder's increasingly isolated and hard-to-read leader.
Russia
Russia
Since then @placeholder-backed forces have seized large swathes of territory on eastern Ukraine.
Ukraine
Ukraine
Ukrainian
Ukraine
The push to arm @placeholder got another boost this week with a report by a group of eight influential foreign policy scholars -- including several former senior Obama appointees.
Barack Obama
Obama
Obama
The push to arm Ukraine got another boost this week with a report by a group of eight influential foreign policy scholars -- including several former senior @placeholder appointees.
Ukraine
Ukraine
Ukrainian
Ukraine
Those urging Obama to go ahead with an effort to arm @placeholder argue that he must make the point that flagrant violations of international order perpetrated by Putin in Ukraine are unacceptable.
Ukraine
Ukraine
Ukrainian
Ukraine
Some Russian experts believe a move to arm @placeholder could backfire, and play into Putin's conspiratorial mindset.
Putin
"The moment @placeholder thinks this weaponry is coming in, he could dramatically escalate things in a very dangerous way to take advantage of the current window," he said.