Pablo Martinez Monsivais/Associated PressPresident Bush with President Hu Jintao of China, center rear, at the Asia-Pacific talks in Chile Saturday.
ANTIAGO, Chile, Nov. 20 - President Bush increased the administration's pressure on Iran on Saturday, saying there were indications that the country was speeding forward in its production of a key ingredient for nuclear weapons fuel, a move he said was "a very serious matter'' that undercut Iran's denials that it was seeking to build weapons.
On the first day here of the annual gathering of Pacific Rim leaders, his first summit meeting since winning re-election, Mr. Bush also tried to re-establish a unified front against the other nuclear challenge facing his second term: North Korea.
In back-to-back meetings with the leaders of China, Japan and South Korea here Saturday morning, Mr. Bush urged each to draw North Korea back into six-nation negotiations. And in a speech later, he issued a direct challenge to North Korea's reclusive leader that echoed President Reagan's demand in 1987 for the dismantling of the Berlin Wall. After the meetings, he said, he was convinced "that the will is strong, that the effort is united and the message is clear to Mr. Kim Jong Il: Get rid of your nuclear weapons programs."
His aides have played down informal intelligence estimates that the country had already produced enough plutonium in the past two years to manufacture six additional nuclear weapons.
Mr. Bush's efforts here underscored his determination to reverse two nuclear projects that appear to have made significant progress while American attention has been focused on Iraq.
In North Korea, he is facing a country that has defied every previous effort he has made to force it to dismantle what it has already built. And in Iran's case, he is clearly skeptical about a European-led effort to suspend the country's manufacture of nuclear material.
He told reporters on Saturday that he was "concerned about reports" that said Iran appeared "willing to speed up processing of materials that could lead to a nuclear weapon." Diplomats had said the day before that Iran had told the International Atomic Energy Agency that it was racing to produce uranium hexafluoride, a gas that can be enriched into bomb fuel, before it begins to observe the temporary suspension of nuclear activity that it negotiated with the Europeans.
Following Mr. Bush's assertion on Saturday that Iran had accelerated its uranium enrichment, Mr. Powell appeared at a news conference here with Foreign Minister Ignacio Walker Prieto of Chile and was asked to provide details to back that up but declined to do so. He said that in the past four years, as a result of American cries of alarm about Iran's intentions, the international community was now "as concerned as we are" about the problem.
The focus of most of Mr. Bush's sessions was North Korea, and one participant said Mr. Bush hinted he would show "some flexibility'' in offering incentives to the North, a subject of furious infighting within the administration.
But a senior American official told reporters this afternoon that could only happen after North Korea returned to the negotiating table. "The North Korean strategy of running out the clock didn't work,'' this official said, referring to the speculation that the North thought Mr. Bush would be defeated on Election Day.
In 2003, Mr. Bush said he "will not tolerate nuclear weapons in North Korea," and in April 2004 he told a convention of newspaper editors in Washington that a nuclear program in Iran was "intolerable" and would be dealt with, starting at the United Nations if necessary. He did not repeat either phrase on Saturday, and the agreement with Europe appears to have halted, at least temporarily, the administration's hopes of taking the Iranian program to the United Nations Security Council this month.
But Mr. Bush's quickness to seize on the Iranian production of uranium hexafluoride was driven, administration officials said, by a sense among his national security aides that there is still time to stop Iran from actually producing a weapon. "We're past that point with North Korea," one senior adviser said recently. "With the North, it's a question of unwinding what's already happened."
So far, there have been three sessions of talks involving North and South Korea, China, Japan, Russia and the United States, but no real agreement on the scope of the North Korean program. Meanwhile, North Korea appears to have reprocessed a trove of 8,000 spent nuclear fuel rods.
In preparation for the meeting on Saturday morning with China's president, Hu Jintao, American officials took the unusual step several weeks ago of passing to Beijing what one senior Asian official called "classified packets" of data intended to convince the Chinese that the North has two weapons programs under way.
Chinese leaders had few doubts that the North has been trying to produce plutonium weapons, and they have not questioned unofficial American intelligence estimates that the North has reprocessed enough plutonium for four to six weapons since inspectors were expelled from the country nearly two years ago.
But until recently China expressed considerable doubts about a second program that the United States believes the North started with help from A. Q. Khan, then the head of Pakistan's nuclear weapons project. Like the Iranian program, which also received extensive aid from Mr. Khan's network in the 1990's, the North's program involves enriching uranium to make bomb fuel. "The Chinese made their own inquiries from Pakistan, and we believe they got confirmation there," said one senior Asian official involved in the Saturday talks with President Bush. "They don't seem to be questioning the validity of that intelligence anymore, at least in private."
But Mr. Bush was clearly concerned that South Korea's president, Roh Moo Hyun, might diverge from the American strategy, and offer the North more aid and investment even before it agrees to surrender its weapons, halt its production of new weapons and allow open inspections.
Iran's intentions are unclear. If it is truly suspending the production of all nuclear fuel, it is unclear why it would work so quickly to finish production of the raw material that is fed into centrifuges and enriched. At low enrichment levels, the fuel could be used to produce nuclear power; at high enrichment levels, it could make the core of a bomb.
American officials said Mr. Bush spoke out because he wanted to highlight the possibility that Iran could cheat on its deal with the Europeans, and to raise the possibility that it had a secret complex of centrifuges that could keep producing bomb fuel. A dissident group operating outside Iran charged this week that Tehran was doing exactly that, but American officials say they cannot verify the claim.
Mr. Bush's day was tense in other ways, as well. He had an unusual encounter with President Vladimir V. Putin of Russia, questioning him over lunch about Mr. Putin's efforts to concentrate more power in the Kremlin. It was the first time Mr. Bush had expressed his concerns in person to the Russian leader.An American official said later that Mr. Putin responded with "a very long explanation, went back deep into Russian history, the Stalinist period'' and said the country was still struggling to "develop a Russian-style democracy.''
The conversation did not appear to satisfy either side, but the American official said it would be the "basis for further conversations."
Then, in an odd scene on Saturday before dinner, Mr. Bush had to rescue his lead secret service agent.
The agent had been blocked from entering the ornate dinner hall and was surrounded by a scrum of shoving Chilean security officers. The president, realizing what was happening, turned around and walked up to the group, reached in to pull his agent free, and walked back into the hall, shaking his head.