President Obama told reporters gathered in Pittsburgh for the G20 Summit Friday that the reason the United States sat on intelligence that Iran was building a nuclear facility for years was to allow intelligence experts to vet it thoroughly.

“It is very important in these kinds of high-stakes situations to make sure that the intelligence is right,” he said.

President Obama, British Prime Minister Gordon Brown, and French President Nicolas Sarkozy announced the existence of the Iranian facility, 100 miles outside of Tehran, at the opening of the Summit. Their three governments presented evidence to the International Atomic Energy Agency that makes clear, Obama said, that the facility would be used for nefarious purposes.

Still, the President wants to err on the side of diplomacy, for now, “I would love nothing more than to see Iran choose the responsible path…when we find that diplomacy does not work, we will be in a much stronger position to, for example, apply sanctions that have bite.”

But Mr. Obama declined to specify what kind of sanctions he would support.

House Republican Leader John Boehner (R-OH) was also concerned over the revelations, but said it should make the world bristle, not roll over, “This revelation should put the international community on notice that its collective willingness to give the Iranian regime ‘one more chance’ is not working…How will we respond if Iran does not let inspectors in? Why should we feel confident they are being honest about anything else?"

Mr. Obama says the intelligence shows the facility violates both IAEA and UN Security Council resolutions, but Iranian President Mahmoud Ahmadinejad said his country was operating by the rules when it revealed the existence of the facility, "It's not a secret facility," Ahmadinejad told reporters at a press conference at the Intercontinental Hotel in New York, "What we did was completely legal."

UN Security Council members Russia and China, who are typically loathe to punish Iran, are also on board in resolving concerns over Iran's nuclear problem.

The permanent members of the UN Security Council and Germany will meet on October 1 to decide on the next steps.