The US and Lithuania are discussing co-operating on Washington’s missile defence system in a move likely to deepen Russian opposition to the plans.

The preliminary contacts with Vilnius come after months of US negotiations with Poland, which have failed to secure a breakthrough. Those talks have been complicated by tensions with Russia, which says US plans to locate 10 missile interceptors in Warsaw and a radar base in the Czech Republic would affect its strategic deterrent – despite US assurances that the missile bases are intended to deal with a threat from Iran, not Russia.