Russia's intervention in Georgia proved to be the spur that drove the US to strike a deal with Poland to build part of the missile defence shield on its territory, an accord that will be signed by Condoleezza Rice, US secretary of state, in Warsaw today.

For months US diplomats sought to avoid exacerbating Moscow's considerable irritation over the missile defence programme by only agreeing to the missile shield - which has little practical benefit to Poland. The US says the missile defence programme is intended to counter the threat of ballistic missiles launched by rogue states such as Iran, not Russia.