The United States and its NATO allies must move forward with developing and deploying a missile shield to protect Europe, with or without Russian cooperation, senior US Senator John McCain said Monday.

"The United States and NATO should waste no time in continuing to develop and deploy the missile defense systems in Europe necessary for our common security -- with Russian cooperation if possible but without it if necessary," he said in a statement.

Russian President Dmitry Medvedev pledged after a North Atlantic Treaty Organization summit in Portugal to work with the alliance on a missile defense system for Europe but insisted Moscow must be an "absolutely equal" partner.

"Either we participate fully, exchange information, are in charge of solving these or those issues, or we do not participate at all," he said, warning that "if we do not participate at all then we would be forced to defend ourselves."

McCain, a longtime backer of US plans to build a defense against ballistic missiles, called Moscow's receptiveness on the issue "a positive step" and said a shield would blunt the threat from "rogue regimes like that of Iran."

The lawmaker, who is the top Republican on the Senate Armed Services Committee, also welcomed NATO's announcement that it hoped to hand Afghan forces responsibility for their war-torn country's security by the end of 2014.

"I also appreciate that this new transition date is a goal, not a guarantee of complete withdrawal," said McCain, who has sharply criticized Obama's stated aim of beginning a US troop draw-down in July 2011.

McCain said US and NATO forces must "focus now" on defeating the Islamist Taliban insurgency, boosting good governance in Kabul, and training Afghan security forces to "take the lead" in combat operations.

"That is how US and NATO troops will return home with victory and honor," he said.