President Obama on Thursday said he is scrapping current plans for a missile defense system in Poland and the Czech Republic that was intended to protect against the threat of a nuclear-armed Iran, but said he is doing so in order to deploy a more flexible system, possibly in those same countries, that his administration said is an "enhancement."

Mr. Obama, in a statement at the White House, said that his "new approach" will "best address the threat posed by Iran's ongoing ballistic missile defense program."

So let me be clear: Iran's nuclear and ballistic missile activity poses a real threat, not just to the United States, but to Iran's neighbors and our allies. The Czech Republic and Poland have been courageous in agreeing to host a defense against these missiles. As long as the threat from Iran persists, we will go forward with a missile defense system that is cost-effective and proven. (Applause.) If the Iranian threat is eliminated, we will have a stronger basis for security, and the driving force for missile defense construction in Europe will be removed."