But whether sending antitank artillery, sophisticated radar systems and other arms and equipment to the beleaguered government forces would do more harm than good is a question still fiercely debated.
Even the most ardent advocates of sending weapons to Kiev say they have no illusions that more firepower will be enough to roll back separatists' territorial conquests in the country's east.
Many share the view of those opposed to arming Ukraine that such a move is likely to antagonize Russian President
But Ukraine has the moral and legal right to defend itself, foreign policy analysts say. And Washington is supposed to be a guarantor of the nation's security, they add, under a 1994 agreement in which Kiev surrendered its nuclear arsenal in exchange for promises from the United States, Britain and Russia to respect its sovereignty.
Fighting intensified on the eve of another diplomatic quest for a cease-fire, this time bringing the leaders of Russia, Ukraine, Germany and France to Minsk, Belarus, on Wednesday. At least 15 people were killed Tuesday, most of them civilians, in a missile attack in the eastern Ukrainian town of Kramatorsk. The separatists and the Ukrainian government blamed each other for the bloodletting.
Obama has said he will consider arming Kiev if the diplomacy fails. But he clearly remains skeptical that sending U.S. arms would bring the two sides closer to a negotiated peace. At a news conference Monday with visiting German Chancellor
Merkel has said repeatedly that arming Ukraine risks provoking Putin and escalating a conflict that has already taken more than 5,300 lives.
Some foreign policy experts have increasingly called for stronger action by the U.S. administration to counter Russian aggression. Among the voices urging military aid for Ukraine is Defense Secretary-designate
Supplying arms to Ukraine carries a "very high" risk of escalating the conflict, but the price of not doing so may also be steep, leading Putin to believe he can violate international borders with impunity, said Kori Schake, a Hoover Institution fellow and National Security Council member in the
"It's a delicate pedal and clutch operation," she said of the correct U.S. stance in the conflict.
Schake said she favors sending arms, as Ukrainians have the right to defend themselves and Russia should be made to pay for the damage it has inflicted.
"But I'm not sure I'm in favor of arming them if it costs us German leadership on the issue," she said, alluding to Merkel's objections.
Putin has used the conflict to cast the United States as an enemy and to rally Russians to the cause of defeating an alleged threat to their security, said Michael McFaul, who was U.S. ambassador to Russia during the Obama administration's "reset" of relations with Russia.
The last straw for Putin was the ouster of ally
Now a political science professor at Stanford University, McFaul supports sending arms but doubts that will lead to resolution of the conflict. He sees little chance of the Ukrainian army recovering territory and expects a violent reaction from Putin.
"But at some point we should let the Ukrainians have a say in their own security," McFaul said. "They are the ones who are going to bear the brunt of this escalation."
Other Russia experts worry that arming Ukraine will validate Putin's view that Washington wants to depose him.
"Russia thinks there is a real security risk coming from the change of power in Kiev, and the more Kiev looks like it is going to be a military client of the United States, the more Russia feels that risk and the more it is willing to put on the line to counter it," said Keith Darden, a professor of international relations and Eurasia expert at American University.
Darden sees the fighting as a war of attrition that Russia, with its $350 billion in currency reserves, will surely be able to survive longer than Ukraine, which is teetering on the verge of bankruptcy with massive debt and $5.4 billion on hand.
The government could face renewed unrest if it runs out of money to fund the army or pay salaries, and it has failed to undertake the reforms it promised in exchange for financial aid, Darden said.
"They're saying, 'You really don't want us to collapse,' and we're saying, 'We really want you to reform,'" the professor said. "They are playing a dangerous game of chicken with us."
The arms Russia has provided the separatists are heavy armor and advanced electronics, but the Kremlin has vastly superior air power it could bring to the fight, Darden said.
"That would be a huge escalation and it would be devastating for the Ukrainian military," he said.