President Bush's national security adviser insisted Sunday the United States is not making concessions to Iran (search), even though Washington has softened its stance against the nation that Bush recently labeled "the world's primary state sponsor of terror."

Stephen Hadley (search), in his first television appearances since becoming national security adviser last month, said the United States is supporting European allies as they try to negotiate an end to Iran's suspected nuclear weapons ambitions. But he said that if those negotiations fail, the Europeans and the United States have agreed to take the matter to the U.N. Security Council.

"We've now got a strategic agenda with the Europeans, and we've also got agreements from the Europeans that if their negotiations do not succeed and Iran resumes its effort to move toward a nuclear capability, then we will go together and take it to the United Nations," Hadley said during a televised interview.

Secretary of State Condoleezza Rice (search) said the Bush administration believes Iran's nuclear disputes with other countries can be resolved diplomatically. But she repeated the president's statement that he keeps all his options open, suggesting that military strikes might be considered if diplomacy fails.

At the request of the Europeans, the United States agreed last week to drop opposition to Iranian membership in the World Trade Organization and to allow some sales of spare parts for civilian aircraft.

"These are not concessions that we are offering to Iran," Hadley said on "Fox News Sunday." "I do not think that the Iranian regime can take much comfort in this because as part of this arrangement, the Europeans now for the first time are talking about Iranian support to terror and the need for this Iranian regime to listen to their people and to give them a greater role in the political process."

The new U.S. stance is a change from Washington's previous hardline position that Iran deserves no reward for simply abiding by an international arms compact that forbids nuclear weapons development. The United States suspects Iran is using a legitimate program to develop nuclear power plants as cover for illegal weapons development — a charge that Tehran denies.

"We hear what they say," Hadley said on CNN. "But their behavior has been suspicious enough that not only the United States but also the Europeans are concerned and think we need some guarantees that make — that are clear that will prevent Iran from getting a nuclear weapon capability."

Iran scoffed at the incentives Saturday. Foreign Ministry spokesman Hamid Reza Asefi said neither threats nor incentives would alter Iran's determination to develop peaceful nuclear technology.

Hadley, who took over Rice's former job as national security adviser when she became secretary of state, said Asefi's remarks aren't surprising during the negotiating process. Hadley also pointed out that Iranian President Mohammad Khatami had said his country is ready to cooperate with the world.

"The negotiation is still going on," Hadley told Fox.

Rice said the United States and Europe are speaking with one voice on the issue of Iran.

"What we were able to achieve over the last few weeks is a really clear, common purpose and common approach," Rice said on NBC's "Meet the Press." "The Iranians can't have a nuclear weapon and that is what everyone has said."