Nato leaders meeting this week are expected to create "a very high-readiness force" to deal with Russian aggression in Ukraine.
The new force could include several thousand troops that will be mobilised for action in any potential 'hotspot' within 48 hours, according to officials.
Nato already has a rapid reaction force but US President Barack Obama and other leaders meeting for a summit in Wales this week are expected to create a new force that would be able to respond more quickly to a crisis.
We will develop what I would call a spearhead ... a very high-readiness force able to deploy at very short notice. This could include several thousand troops, ready to respond where needed with air, sea and special forces support.
Were the Russians -as Barack Obama claims - weighed down by sanctions, or where the Ukrainians looking to cut their losses?
The new president of the European Council could be "very important" for David Cameron.