MUNICH — Vice President Joe Biden delivered a clear message to Iran, saying Saturday the U.S. is willing to talk, but will act to isolate and pressure Tehran if it does not abandon its nuclear ambitions and support for terrorism.

In a speech to international leaders and security experts here, Biden said the U.S. will strive to act preventively to avoid having to choose between the risks of war and the dangers of inaction.

But he held out the option that the U.S. could take pre-emptive action against Iran if necessary to stop a crisis before it starts. The U.S., he said, will "continue to develop missile defenses to counter a growing Iranian capability, provided the technology is proven and it is cost effective."

At the same time, he said that if Tehran gives up its nuclear program and stops backing terrorists, there will be meaningful incentives.

"We will draw upon all the elements of our power — military and diplomatic, intelligence and law enforcement, economic and cultural — to stop crises from occurring before they are in front of us," Biden told the gathering.

During much of the morning Iranian parliamentary speaker Ali Larijani was in the room, but it was unclear if he was there as Biden spoke. There is no indication if the two men will meet.

Biden's speech laid out for the first time to an international audience the Obama administration's foreign policy tenets, and emphasized diplomacy and cooperation.