LOS CABOS, Mexico (Reuters) - Russian President Vladimir Putin reiterated Moscow's strong opposition to the U.S. missile defense system on Tuesday, saying that President Barack Obama's re-election would not end the dispute and insisting on joint development of the shield.

"I think that the missile defense issue will not be solved regardless of whether Obama is elected or not," he told reporters at the end of Group of 20 summit in Mexico.

"I think that something can radically change only in the case if the U.S. agrees with our proposal which says that Russia, Europe and U.S. were equal participants of this process," said Putin.

Moscow says the interceptors that the United States and NATO are deploying as part of the system will be able to destroy Russian warheads in flight by about 2018, upsetting the post-Cold War balance of power.

Washington maintains that the missile defense system - which is to be deployed in four phases by about 2020 - is intended to counter a potential threat from Iran and poses no risk to Russia.

(Reporting by Gleb Bryanski.; Writing by Paul Eckert; editing by Christopher Wilson)