This assistance would come in the form of so-called "defensive lethal aid", which could include anti-tank, anti-air and anti-mortar systems. A US official said that military leadership supports defensive lethal aid being part of the discussion, but the administration is still trying to assess what reaction it could elicit from the Russian government, which the US maintains is backing rebels in eastern Ukraine.

In a recent interview, US President Barack Obama alluded to concern in the international community that President Vladimir Putin is further isolating Russia, and bypassing opportunities to de-escalate the conflict.

"What is absolutely true is that if you have a leader who continually rives past the off ramps that we've provided, given the size of the Russian military, given the fact that Ukraine is not a NATO country and so as a consequence there are clear limits in terms of what we would do militarily, you know, Putin has not been stopped so far," Obama said.

The US official said the arms option came back to the forefront  following Russian advances and weapons shipments into Ukraine in recent weeks. But the US military leadership feels any arms shipments to Ukraine must be part of a broader package of options. Ben Rhodes, Obama's deputy national security adviser, said on Monday that sending lethal aid to Ukraine is not a solution to the escalating situation there.

"We don't think the answer to the crisis in Ukraine is simply to inject more weapons and get into that type of tit-for-tat with Russia," Rhodes said.

"We think the answer is to apply pressure, try to get them to the table  with the separatists so we can see a peaceful de-escalation," Rhodes said, adding that Obama and German Chancellor Angela Merkel would likely discuss Ukraine when they meet at the White House next week.

Latest News from World News Desk