My first impression went back to Reagan's 1983 invasion of Grenada, Urgent Fury as it was called. It was a quick operation that had an enormous psychological impact on public opinion after the Vietnam debacle. Russia needs to show the world, especially the US, NATO and border states that they mean to react- with urgent fury- to safeguard their interests.

Russia will continue to foster rebels throughout the ex-Soviet states but will at times feel it necessary to demonstrate their might. Ukraine has no doubt got the message today.