"It's very clear to us that al-Qaeda has been able for the past 18 months or so to establish a safe haven along the Afghan-Pakistan border area that they have not enjoyed before, and that they're bringing in operatives into the region for training," he said.
Hayden added that that those operatives "wouldn't attract your attention if they were going through the customs line at Dulles (airport, outside Washington) with you when you're coming back from overseas - who look Western."
Washington has sought reassurance that Pakistan's new coalition government will keep the pressure on extremist groups using the country's lawless northwest frontier as a springboard for attacks in Afghanistan and beyond.
Over the weekend, Pakistan's new prime minister, Yousaf Raza Gilani, pledged to make the fight against terrorism his top priority. But he said peace talks and aid programs could be more effective than weapons in fighting militancy in tribal areas along the Afghan border. It was the new government's latest rebuke of President Pervez Musharraf's military tactics, which many Pakistanis believe have led to a spike in domestic attacks.
On Sunday, Hayden declined to comment on reports that the U.S. might be escalating unilateral strikes against al-Qaeda members and fighters operating in Pakistan's tribal areas out of concern that the pro-Western Musharraf's influence might be waning. Hayden only would say that Pakistan's cooperation in the past has been crucial to U.S. efforts to stem terrorism there.
"The situation on the Afghanistan-Pakistan border presents clear and present danger to Afghanistan, Pakistan, the West in general and United States in particular," he said. "Operationally, we are turning every effort to capture or kill that leadership from the top to the bottom."
On Iraq, Hayden said it could be "years" before the central government might be able to function on its own without the aid of U.S. combat forces. Hayden said he would defer to the specific assessments of Gen. David Petraeus, the top U.S. commander in Iraq, and Ryan Crocker, top U.S. diplomat in Baghdad, who return to Washington next month to report to Congress.
Hayden spoke on NBC's "Meet the Press."