Napolitano says U.S. must be vigilant after bin Laden

U.S. Homeland Security Secretary Janet Napolitano speaks to Reuters in Washington, March 30, 2011.

ATLANTA (Reuters) - Al Qaeda and its allies will keep targeting the West despite the killing of Osama bin Laden and the United States must remain "ever vigilant," Homeland Security Secretary Janet Napolitano said on Saturday.

Napolitano said the U.S. government had nevertheless not formally raised alert levels in its National Terrorism Advisory System since U.S. commandos killed the al Qaeda leader at a compound in Pakistan nearly a week ago.

"What that means is that we have no specific, credible intelligence right now that would indicate that we do so. But we are constantly, with our intelligence partners feeding into us, evaluating that posture," she told an audience at the Atlanta Press Club.

While Napolitano hailed bin Laden's killing as "probably one of the most significant achievements yet" in the U.S. fight against terrorism, she warned against the United States and its Western allies lowering their guard.

"There really is no doubt that al Qaeda, or an al Qaeda affiliate, or those inspired by that ideology, will continue to focus their attacks on the West," she said. "What this means is that we have to remain ever vigilant."

Napolitano spoke as a senior U.S. intelligence official in Washington told journalists that the compound in Pakistan where bin Laden was killed was an "active command and control center" for the al Qaeda leader.

Addressing U.S. government efforts to curb illegal immigration on its southern border, Napolitano, a former Arizona governor, said federal authorities were making progress in improving border security.

"There has never been a larger, more sustained and better effort," she said.

Napolitano rejected criticism by some states that President Barack Obama's administration was not doing enough to halt the unlawful influx of migrants. States like Arizona and Georgia have toughened measures against illegal immigrants.

"I think these efforts at the state-by-state level ... they're predicated on a falsity. The falsity is that there has been nothing done, that the border somehow is out of control. That is incorrect," she said.

(Editing by Pascal Fletcher and Chris Wilson)