The Ukraine crisis does not mark the start of a new Cold War, but Russia’s isolation will only deepen if it stays on its current course, President Barack Obama has warned.

In Brussels, Obama also called on NATO nations to stand together, insisting if the West remained united, Russians would recognise they could not have success through brute force.

“What we will do, always, is uphold our solemn obligation. Our article 5 duty to defend the sovereignty and territorial integrity of our allies. And in that promise we will never waver. NATO nations never stand alone. Today NATO planes patrol the skies over the Baltics and we’ve reinforced our presence in Poland. And we are prepared to do more. Going forward every NATO member state must step up and carry its share of the burden,” Obama said.

Obama and NATO General-Secretary Anders Fogh Rasmussen have held talks in Brussels over additional steps to Russia’s annexation of Crimea. Those discussions reportedly included enhanced defence plans and military exercises, as well as regional deployments.