WARSAW, Aug. 20 (Xinhua) -- U.S. Secretary of State Condoleezza Rice and her Polish counterpart Radoslaw Sikorski formally signed here Wednesday an agreement to deploy parts of the U.S. global missile shield in the East European country.

　　Polish and U.S. negotiators reached the deal last Thursday to host parts of the U.S. global missile shield, including a battery of Patriot air defense missiles in Poland, after Washington improved the terms of the deal amid the Georgia crisis.

　　The agreement, reached after 18 months of tough bargaining, reportedly provides for deploying Patriot missiles in Poland and strengthening Polish-U.S. military cooperation. It also includes a declaration of U.S. military cooperation in case of a threat to Poland from third states.

　　The United States plans by 2011-2013 to install a base for 10 interceptor missiles in northern Poland to protect the U.S. and Europe from possible future attacks from what it calls "rogue" states such as Iran.

　　Warsaw has been lobbying Washington to provide a THAAD or Patriot-type air defense system in exchange for a Polish green light for hosting the silos.

　　Russia objects the anti-missile shield plan, saying it will threaten Russian national security. Moscow has warned that it will target its missiles at the system if it is deployed in Poland.