Leaders Gather for Nuclear Talks as New Threat Is Seen

WASHINGTON — Three months ago, American intelligence officials examining satellite photographs of Pakistani nuclear facilities saw the first wisps of steam from the cooling towers of a new nuclear reactor. It was one of three plants being constructed to make fuel for a second generation of nuclear arms.

The message of those photos was clear: While Pakistan struggles to make sure its weapons and nuclear labs are not vulnerable to attack by Al Qaeda, the country is getting ready to greatly expand its production of weapons-grade fuel.

The Pakistanis insist that they have no choice. A nuclear deal that India signed with the United States during the Bush administration ended a long moratorium on providing India with the fuel and technology for desperately needed nuclear power plants.

Now, as critics of the arrangement point out, the agreement frees up older facilities that India can devote to making its own new generation of weapons, escalating one arms race even as President Obama and President Dmitri A. Medvedev of Russia sign accords to shrink arsenals built during the cold war.