A group of senior foreign policy experts is pushing the White House to arm Ukrainian forces with lethal weapons because of the recent surge in fighting in the east of the country.

This would be a significant policy shift for the White House which has so far opposed sending what's known as "lethal aid" (read weapons) to Kiev because it didn't want to risk escalating the situation there.

However, since the situation is clearly already escalating, the White House may be more receptive to giving Kiev what it says it needs.

"Well there are Russian military forces on Ukrainian territory without the permission of the Ukrainian government. I think most countries would consider that an invasion," was how one of the report's author's, Steven Pifer, former US Ambassador to Ukraine, put it to me this evening.