Calls in the US to supply Kyiv with weapons have been met with deep skepticism in Western Europe. As rebels in Ukraine gain ground, NATO is divided over how to prevent a broader conflict.
The White House's pick for defense secretary said on Wednesday that he was "inclined" to support supplying Ukraine with "lethal arms."
"We need to support the Ukrainians in defending themselves," Ashton Carter said during a Senate confirmation hearing on Wednesday.
White House Deputy National Security Adviser Ben Rhodes told CNN earlier in the week that the administration was reviewing the question of arms deliveries.
Opposition within NATO
But across the Atlantic, major European allies have been frank in their opposition. French Defense Minister Jean-Yves Le Drian told reporters that Paris has "no intention of delivering weapons at this stage to Ukraine." His comments echoed the long-standing German position, which Chancellor Angela Merkel reiterated during a visit to Budapest on Monday.
"Germany will not support Ukraine with weapons," Merkel told reporters. "I am firmly convinced that this conflict cannot be resolved militarily."
Berlin's opposition to weapons deliveries could play a critical role in White House deliberations. White House adviser Rhodes has called Merkel the "most important international partner on Ukraine." He said that Obama and the chancellor would discuss Ukraine face-to-face during a "very important meeting" at the White House on February 9.
Kimberly Marten, an expert on Russian foreign policy at Columbia University, said that the reservations in Europe were well founded.
"There does not appear to be an endgame in the weapons proposal," Marten told DW via email. "What will the US do if the fighting becomes worse and expands to more Ukrainian territory if we send in weapons?"
Billions in proposed military aid
Pro-Russian rebels have gained more than 500 square kilometers of territory in the Donbas region in recent weeks. Kyiv says the rebels are backed by 9,000 Russian troops, while the US has said Russians are present in specialist roles. Moscow denies that its forces are deployed on Ukrainian territory.
In a report entitled "Preserving Ukraine's Independence and Resisting Russian Aggression: What the United States and NATO Must Do," former American diplomats have called on the White House to provide Kyiv with $1 billion (870 million euros) in annual military assistance through 2017.
That would make Ukraine the fifth largest recipient of US foreign assistance - behind Israel, Afghanistan, Egypt, and Pakistan - if 2014 levels are used as a guide. The proposed package would include light anti-armor missiles to help the Ukrainian military defend against rebel armor, which the West says is supplied by Russia.
"The United States and NATO should seek to create a situation in which the Kremlin considers further military action in or against Ukraine too costly to pursue," the report said. "Moreover, if confronted by a strong Western response in support of Ukraine, the Kremlin will be far less tempted to challenge the security or territorial integrity of other states, including NATO members Estonia and Latvia."
Proxy war in Europe?
But according to Marten, sending weapons would only fuel a more severe spiral of escalation. "The plan to send weapons to Ukraine assumes that they will deter Russia and cause Putin to back down," Marten said. "Everything we know about Putin's personality and history suggests instead that he will ramp up the fighting."
The US and the Soviet Union engaged in bloody proxy wars during the Cold War. But these surrogate conflicts were fought outside Europe, according to Angela Stent, director of the Center for Eurasian, Russian and Eastern European studies at Georgetown University. The current conflict in Ukraine has thrown the old playbook out the window.
"We don't have rules of the game anymore," Stent told DW. "I guess the West assumed that we wouldn't be in a situation like this again."