President Bush called it "naive" on Thursday to think that Iran couldn't transfer nuclear enrichment capabilities from energy development to atomic bomb production.
Bush rejected Iran's argument that its nuclear activities are intended only for a civilian energy program.
"If that's the case, why did they have a secret program?" he said at a Rose Garden news conference with British Prime Minister Gordon Brown.
Bush added that he regards Tehran as "untrustworthy" on the topic. Further, even if their activities are only energy related now, that could change, the president said.
"To say that well, OK, it's OK to let them learn to enrich and assume that that program and knowledge couldn't be transferred to a program — a military program — in my judgment is naive," he said.
'I make no apology'
Brown, in Washington for his second U.S. visit since replacing Tony Blair as prime minister last June, supported his host's tough stance against Iran. He said he is talking to European leaders about extending European sanctions, to include investments and liquified natural gas; the United States is also pushing for a new, tougher round of United States against Tehran.
"I make no apology for saying that we will extend sanctions where possible on Iran," the British leader said. "Iran is in breach of a nonproliferation treaty. Iran has not told the truth to the international community about what its plans are."
Brown said it also was important to monitor the effect sanctions are having in Iran, where there is high inflation and the regime is not properly disclosing the effect of the sanctions.
Brown and Bush have not been especially close, and had a somewhat frosty first meeting in July. Ties have been complicated by Brown's decision to draw down British troops in Iraq.
Substantial progress in Basra cited
But the plan to reduce British troop numbers from about 4,000 to 2,500 is now on hold. It had been due to begin within weeks but was delayed following a recent spike in violence in the oil-rich southern city of Basra. Brown says it would remain suspended until Iraqi security forces show progress in driving out militias.
Brown said Iraq, as well as Afghanistan, where British troops also serve alongside the United States, consumed much of the discussion between the two leaders in the Oval Office.
"We believe that our program of over-watch in Basra and in the south of Iraq is making substantial progress," he said.
Bush went out of his way to lavishly praise the contributions — and to honor the sacrifices — of British troops in Iraq. He commented on the "brilliance" of British helicopter crews during recent fighting to support an Iraqi offensive in the southern Basra province. Bush said he filled in Brown on what his top Iraq officials have been telling him, and that Brown did the same.
"The key thing there is that we're working very closely together and that we're making progress," the president said.
The British leader arrived in the U.S. on Tuesday, attending a session of the United Nations and meeting with investment executives on Wall Street in New York before coming to Washington.
He and his wife, Sarah, were returning to the White House in the evening for an intimate dinner with the Bushes in the residence.
Relations with Bush contrast with the chummy bond between the prime minister's predecessor and the president. But the British leader said before his U.S. trip that he now hopes he can help strengthen ties, and that coordinated efforts to shore up the world economy and work on climate change can reinforce ties between Europe and Washington that were frayed by the Iraq war.
And even though Blair's popularity suffered from his relationship with Bush, Brown seemed to be making a special effort to align himself with the U.S. leader, with effusive praise for Bush, support on Iraq and Iran and even some gentle joking. The British leader said they had had an "excellent meeting" and said "the bond between our two countries is stronger than ever" as a result.
"The world owes President George Bush a huge debt of gratitude for leading the world in our determination to root out terrorism and to ensure that there is no safe haven for terrorism and no hiding place for terrorists," Brown said. "As Tony Blair said, we stand shoulder-to-shoulder with the American people and with President Bush. And I continue to stand shoulder-to-shoulder with him in rooting out terrorism wherever we find it in any part of the world which puts freedom, democracy and justice at risk."
Bush made an effort, too.
When a British reporter asked Brown, "Some people would suggest that the special relationship is a little less special than it was under Mr. Brown's predecessor. Is that true or false?," Bush interjected with a forceful answer.
"False," he said. "Our relationship is very special. And I'm confident future presidents will keep it that way. There's just such a uniqueness in the relationship. That's not to say you can't have other friends, and we do. But this is a unique relationship. It truly is. And I value my personal friendship, as well as our relationship between our countries. Look, if it wasn't a personal relationship, I wouldn't be inviting the man to a nice hamburger or something."
Brown also met Thursday with all three major U.S. presidential candidates. In successive 45-minute meetings with the candidates at the British ambassador's residence, Brown discussed the Iraq war, global warming and his country's relationship with the U.S. with Republican John McCain and Democrats Hillary Rodham Clinton and Barack Obama, one of whom will be his ally come January.
Brown declined, at Bush's side, to discuss which candidate he preferred to replace Bush as U.S. president in 10 months' time.
"What I was convinced of, after talking to each of them and talking about the issues that concern them and concern the world, is that the relationship between America and Britain will remain strong, remain steadfast, that it will be one that will be able to rise to the challenges of the future," he said.