Bush administration says the proliferation activities of Pakistani nuclear scientist Abdul Qadeer Khan and his associates caused a great deal of harm. But U.S. officials are declining to criticize the decision by Pakistani President Pervez Musharraf to pardon Mr. Khan.
Though the Bush administration has made the fight against nuclear proliferation a top priority, State Department spokesman Richard Boucher says the legal status of Mr. Khan is not a matter for the United States to judge.
At a news briefing, Mr. Boucher said the United States "values" the pledges President Musharraf has made to prevent further proliferation, and believes his government is making serious efforts to end the activities of Mr. Khan and his network.
He said the specifics of what happens to Mr. Khan may be less important than assuring that the leakage of Pakistani nuclear technology is halted.
"I don't think it's a matter for the United States to sit in judgment on," said Mr. Boucher. "We think what's important in this cases is really two things. One is that the network and the individuals that were doing this in Pakistan, or from Pakistan, be found out, stopped, and prevented from making such transfers again. And second of all, that the information that they develop in their investigation is shared with the international community, because the international community as a whole needs to go after this network, that extends far beyond Pakistan."
President Musharraf assured Secretary of State Colin Powell in a telephone conversation in October of 2002 that any Pakistani proliferation activities had ceased, and there have been no public suggestions by U.S. officials that there have been instances since then.
A senior U.S. diplomat who spoke to reporters here said the possibility of a political backlash against President Musharraf for punishing Mr. Khan - acclaimed as the father of Pakistan's nuclear weapons program - may have been a factor in the decision to pardon him.
But he suggested that Mr. Khan still might face restrictions on his activities and that the United States would closely follow what happens to other Pakistani scientists being questioned about leaking nuclear secrets.
The senior official also would not rule out the possibility the affair might lead to renewed U.S. nuclear sanctions against Pakistan, but he said any such decision would require a complex review and would not come soon.