Poland's prime minister has rejected the latest terms offered by the US to host a missile defence shield.
Donald Tusk said any deal must increase Poland's own security, and he dismissed the latest offer as unsatisfactory.
"We are ready to co-operate but we are waiting for an answer from the American side," Mr Tusk told a news conference.
The US wants to place 10 interceptors missiles in Poland as part of a defence shield against possible attack - a move condemned by Russia and China.
The US is also seeking permission to build a radar station in the Czech Republic as part of the defence shield plans.
Russia has said the project would upset the military balance in Europe and warned it could have no choice but to point its own missiles at the installations.
