WARSAW, Aug. 18 (Xinhua) -- Poland's agreement to a U.S. missile shield on its territory will impair the country's security and start a new arms race, Greenpeace warned Monday.

　　The United States and Poland sealed Thursday an initial accord on the installation of a missile shield in Poland. Parts of the system will also be erected in the Czech Republic.

　　As an extra safety measure Poland is also to receive a unit of U.S. Patriot missiles.

　　In a statement sent to Polish news agency PAP, Greenpeace warned that the shield would only escalate a new arms race. "No weaponry or threats of its use can guarantee a safe future", the organization said, adding that the shield "was not really a shield but a new, offensive sword embodying the Bush administrations dreams about planetwide preventive strikes."

　　Greenpeace also reminded that the U.S. Missile Defense Agency (MDA) itself admitted that the Polish and Czech installations would primarily protect radar systems in Britain and Greenland, and that in case of an attack on the U.S. the Polish and Czech installations would be the first to come under fire.

　　No amount of Patriot missiles will ensure Poland's safety in case of conflict, Greenpeace warned.