PHUKET, Thailand — Stiffening the American line against Iran, Secretary of State Hillary Rodham Clinton warned Wednesday that the United States would consider extending a “defense umbrella” over the Middle East if the country continued to defy international demands that it halt work that could lead to nuclear weapons.
While such a defensive shield has long been assumed, administration officials in Washington acknowledged Wednesday that no senior official had ever publicly discussed it. Some of the officials said the timing of Mrs. Clinton’s remarks reflected a growing sense that President Obama needed to signal to Tehran that its nuclear ambitions could be countered militarily, as well as diplomatically.
It also signified increasing concern in Washington that other Middle East states — notably Saudi Arabia and Egypt — might be tempted to pursue their own nuclear programs for fear Iran was growing closer to realizing its presumed nuclear ambitions.
Mrs. Clinton later clarified her comments on Iran, delivered in advance of a regional meeting here, saying her warning that the United States might create such an umbrella did not represent any backing away from the Obama administration’s position that it must prevent Tehran from obtaining a bomb capability. But her words suggested that the administration was developing a strategy should all efforts at negotiation fail.
Her statement also came as Iran’s internal divisions and crackdown on post-election protests have complicated Mr. Obama’s pledge to “engage” Iran directly. Iranian officials have hinted that they will present new proposals on the nuclear program, and American officials have said their offers to negotiate stand.
Speaking during a televised town hall meeting in Bangkok, Mrs. Clinton said, “We want Iran to calculate what I think is a fair assessment, that if the U.S. extends a defense umbrella over the region, if we do even more to support the military capacity of those in the gulf, it’s unlikely that Iran will be any stronger or safer, because they won’t be able to intimidate and dominate, as they apparently believe they can, once they have a nuclear weapon.”
Asked about Mrs. Clinton’s comments, Sir Nigel Sheinwald, the British ambassador to the United States, said, “I don’t think it should be read as an acceptance of an Iranian nuclear weapon” but rather as a statement intended to “reassure our partners in the gulf.”
A senior White House official said he believed that Mrs. Clinton was speaking for herself and that she was, as she insisted, restating existing policy.
Mrs. Clinton’s invocation of a defense umbrella is reminiscent of the so-called nuclear umbrella that Washington extends to its Asian allies: implicitly, the promise of an American reprisal if they are attacked by nuclear weapons. But she did not use the term nuclear, and a senior State Department official cautioned that her remarks should not be interpreted to mean that.
After meeting the foreign ministers of China, Russia, Japan and South Korea, Mrs. Clinton also said that the United States would not offer new incentives to North Korea to return to negotiations. She said all of the other nations that had engaged in talks with North Korea in the past five years were united in demanding that North Korea undertake a “complete and irreversible denuclearization” before receiving any economic or political incentives from them.
She did not detail the steps that would be part of such a process, though she confirmed that they could include the disabling of the Yongbyon nuclear complex. Last year, North Korea began to dismantle that complex, where it runs a nuclear reactor and reprocess fuel rods to recover plutonium, but it vowed in June to restart production there.
The United States has had an uncharacteristically visible presence at this gathering of the Association of Southeast Asian Nations, or Asean. It signed a friendship treaty with Asean’s 10 members and called on one country, Myanmar, to release the imprisoned pro-democracy leader Daw Aung San Suu Kyi.
Israel’s minister of intelligence and atomic energy, Dan Meridor, told Israeli Army radio: “I was not thrilled to hear the American statement from yesterday that they will protect their allies with a nuclear umbrella, as if they have already come to terms with a nuclear Iran. I think that’s a mistake.”
Mrs. Clinton said she was trying to make even starker the choice Iran faced if it did not agree to abandon its program.
The administration has talked about bolstering the military capacity of Iran’s neighbors in the Persian Gulf so they could better meet the threat of a heavily armed Iran. It has also defended the proposed missile defense system in Eastern Europe as a potential shield against Iran.
“It faces the prospect, if it pursues nuclear weapons, of sparking an arms race in the region,” Mrs. Clinton said. “That should affect the calculation of what Iran intends to do, and what it believes is in its national security interest.”
On North Korea, Mrs. Clinton tried to project a united front, saying that China, Russia, Japan and South Korea had pledged to carry out the United Nations sanctions adopted in June against the North after its recent nuclear and missile tests.
Mrs. Clinton also reiterated concerns that North Korea might be transferring nuclear technology to Myanmar, which American officials refer to by its former name, Burma. She is to deliver a statement on North Korea on Thursday. In an excerpt provided to reporters, the tone remained unyielding, but the United States pledged to give North Korea “significant economic and energy assistance” if it undertook a verifiable denuclearization.
At the ministers meeting, Mrs. Clinton demanded that Myanmar release Mrs. Aung San Suu Kyi, who could face years in prison on charges that she violated her house arrest. “It’s so critical that she be released from this persecution that she has been under,” she said later at a news conference. “If she were released, that would open up opportunities, at least for my country, to expand our relationship with Burma, including investments in Burma.”
American officials met with diplomatic officials from Myanmar later to reiterate Mrs. Clinton’s demand.
Mark Landler reported from Phuket, Thailand, and David E. Sanger from Washington.
