It was a rough week for an administration that is touting its record on national security.

First came the controversy over the leak of a new National Intelligence Estimate that says the Iraq war has made the terrorist threat worse. Then came a rush of bad news about the resurgence of the Taliban in southern Afghanistan, where it is fiercely fighting NATO forces.

But most astonishing was a series of bitter and public ripostes between the visiting presidents of Afghanistan and Pakistan, both U.S. allies, over who’s to blame for the Taliban’s return. Afghan President Hamid Karzai says (with evidence on his side) that Pakistan permits hard-line Islamists to train and headquarter in its tribal regions; Pakistani leader Pervez Musharraf heaps scorn on the charges.

This is no mere tiff between competing politicians. The Taliban attacks in southern Afghanistan have become so bad that Gen. James Jones, the senior NATO commander, has been begging for more forces. The Karzai-Musharraf hostility reflects a problem that could drag Afghanistan down and ensure an ongoing haven for al-Qaida and other terrorists.

So what’s an American leader to do? President Bush invited Karzai and Musharraf to an extraordinary White House tête-À-tête Wednesday night. He planned to urge them, over dinner, to iron out their differences. “It will be interesting for me to watch the body language of these two leaders to determine how tense things are,” Bush said, half-joking, at a news conference Tuesday. Karzai added, sotto voce, “I’ll be good,” a line that only partly hid his antagonism toward Musharraf.

“It’s an important dinner,” Bush added. Important indeed.

While Musharraf has cooperated in the hunt for al-Qaida operatives in Pakistan, under heavy U.S. pressure, his record on controlling Islamic extremists at home has been far more spotty. (The Pakistan military had close ties with the Taliban until the 2001 U.S. invasion.) In recent years the Pakistani leader did send tens of thousands of troops into tribal regions where foreign jihadis, including al-Qaida militants, were hiding.

But early this month the Pakistani government signed a peace pact with tribal leaders in North Waziristan, whom many believe are fronts for the Taliban. Jihadist Web sites are trumpeting the agreement as a Taliban triumph.

When I asked Musharraf, at a Council on Foreign Relations meeting, whether he had handed the Taliban a victory, he vociferously denied it. “We reached an agreement with tribal elders to counter the Taliban,” he claimed.

He argued that heavy use of military force against local Pakistani Pashtun tribes could drive them into an alliance with the Taliban. “Our idea is to get them away from the Taliban, with all of our military behind them.” Supposedly the tribal leaders are going to prevent foreign militants from entering their areas, but few believe this. The agreement leaves unclear what the Pakistani military will do if the agreement is flouted.

“My initial impression was that this was a deal signed by the Taliban,” Afghan leader Karzai said bluntly yesterday. He said the test would be whether “the terrorists will not be allowed to cross over (from Pakistan) into Afghanistan” to assassinate Afghans and attack coalition troops. A top female Afghan educator was assassinated just this week.

I also asked Musharraf about Karzai’s charge that former Taliban leader Mullah Omar was hiding in Pakistan. Karzai says his intelligence chief gave the Pakistanis GPS coordinates, phone numbers and addresses for Omar in the Pakistani city of Quetta. Musharraf claimed the numbers were outdated and “useless” and that “Mullah Omar never came to Pakistan after 1995.”

When told that Jones said the Taliban was directing the insurgency from Quetta, Musharraf retorted: “That is the most ridiculous statement.”

Ridiculous? The bottom line is that Taliban insurgents are crossing the Pakistani border to destabilize Afghanistan and, if not stopped, will undercut what progress has been made there during the last five years. Bush, who needs Musharraf’s cooperation against al-Qaida, cannot ignore the need to press harder on the Taliban issue.

“This is an extremely important dinner, not just for getting the two individuals together,” says New York University’s Barnett Rubin, one of the top U.S. experts on Afghanistan. “If the United States can’t deliver the end of the Taliban sanctuary … then it signals we are not serious about succeeding in Afghanistan.”

So the president had plenty to discuss with his guests between appetizers and dessert.