The National Nuclear Security Administration said Wednesday it is ready to begin security upgrades on the final Russian nuclear warhead site identified in a 2005 joint statement signed by President George W. Bush and Russian President Vladimir Putin. The statement, signed at Bratislava, Slovakia, committed Russia and the United States to cooperate on nuclear security matters. The administration, a part of the US Energy Department, later was designated as the lead organization to upgrade security at nine Russian nuclear warhead facilities. Eight have been completed. "Significant progress has been made to upgrade and improve security at sites within Russia, and with this final site, NNSA will take another significant step toward meeting its commitments under the 2005 Bratislava agreement," William H. Tobey, the agency's deputy administrator for nuclear nonproliferation, said in a statement. The security upgrades are designed to protect against theft or attack by terrorists.