"We have made a decision about what will be best to protect the American people as well as our troops in Europe and our allies," Obama said in an interview with CNN.
"If the byproduct of it is that the Russians feel a little less paranoid and are now willing to work more effectively with us to deal with threats like ballistic missiles from Iran or nuclear development in Iran, you know, then that's a bonus," Obama said.
Obama on Thursday announced abandon of the Bush-era controversial missile defense shield program in Eastern Europe, but unveiled a "phased, adaptive approach" for missile defense in the continent.
"This new approach will provide capabilities sooner, build on proven systems and offer greater defenses against the threat of missile attack than the 2007 European missile defense program," Obama said at a brief news conference in the White House.
U.S. officials said the Obama administration would instead use Patriot missiles and newly developed SM-3 missiles that intercept enemy launches before an offensive missile enters the atmosphere to contend with an Iranian threat.
The latter system would be deployed initially on U.S. ships in the Mediterranean, not in Russia's old area of influence in Eastern Europe.
U.S. Defense Secretary Robert Gates told a press conference on Thursday that the first SM-3 systems will be deployed on ships and by 2015 the military hope to have established land-based SM-3 in stallions.
The Washington Times quoted an unidentified senor White House official as reporting on Friday that the locations for those land-based system "haven't been picked yet."