WASHINGTON - Stopping Iran from acquiring nuclear weapons is an "imperative" for the United States, which is taking a more active role in pursuing that goal, Secretary of State Hillary Rodham Clinton said this morning.

Testifying before the House Foreign Affairs Committee, Clinton cited Iran and its nuclear program as among the administration's highest-priorities.

"We are deploying new approaches to the threat posed by Iran and we're doing so with our eyes wide open and with no illusions," she said.

"We know the imperative of preventing Iran from obtaining nuclear weapons," she added. "After years during which the United States basically sat on the sidelines, we are now a full partner" in international talks on Iran.

The committee chairman, Rep. Howard Berman, D-Calif., asked Clinton how much time it would take to get results on Iran. She did not reply directly but said the administration believes it has set the stage for progress by interacting more directly with allies and by reaching out to the Iranian authorities.

"It is going to be a more successful engagement if our partners around the world understand they must work with us," including on consultations aimed at imposing tougher sanctions on Iran, Clinton said.

"The fact that we are engaging ... actually gives us more leverage with other nations."

In her opening remarks to the panel, Clinton said the core goal of President Barack Obama's anti-terror strategy is to defeat al-Qaida and prevent its return to Afghanistan.