"A lot of terrorists are being trained and harbored in Pakistan," said Ruppersberger, the top Democrat on the House intelligence committee. "That's a serious problem."
al-Qaida in Pakistan last year said in a newly released video that his captors will kill him if the U.S. doesn't meet their demands.
"My life is in your hands, Mr. President," veteran development worker Warren Weinstein said in the video, which was posted late Sunday on several militant websites. "If you accept the demands, I live; if you don't accept the demands, then I die."
Weinstein, 70, was abducted last August in the eastern city of Lahore. Al-Qaida has demanded that the United States halt airstrikes in Afghanistan and Pakistan and free terror suspects from Guantanamo Bay.
In the video, Weinstein addressed President Barack Obama directly: "It's important you accept the demands and act quickly and don't delay. There'll be no benefit in delaying. It will just make things more difficult for me."
The White House expressed concern for Weinstein and condemned his kidnapping, but said Monday it does not and would not negotiate with al-Qaida. Obama and Afghan President Hamid Karzai signed an agreement last week to keep U.S. forces in Afghanistan to fight terrorism and train Afghans for at least a decade after U.S. combat troops withdraw in 2014.
Meanwhile, the U.S. government continues to prosecute alleged terrorists. Khalid Sheikh Mohammed, the self-proclaimed mastermind of the attacks of the Sept. 11, 2001, and four other men were arraigned Saturday on charges related to the deaths of nearly 3,000 people at the World Trade Center and the Pentagon and on United Airlines Flight 93.
Marylanders continue to make up part of the U.S. forces in Afghanistan; there are 523 members of the Maryland National Guard serving in eight units based in Kabul, Bagram, Helmand and Kandahar.
Brig. Gen. Charles W. Whittington Jr., the highest-ranking Maryland Guard member in that country, said he has seen progress in the Afghan security forces the U.S. is training and in life there generally.
"You see kids out on the street," Whittington said by phone from Kabul. "You see people walking around in the parks here. … You can tell that our presence here makes a difference."
Ruppersberger traveled to the volatile Afghanistan-Pakistan border region during his visit last week. His observations matched those of other analysts, who warn that the tribal areas of northwestern Pakistan have provided a haven and staging ground for attacks on NATO forces in Afghanistan.
"That relationship with Pakistan has to improve for us to continue to effectively protect our country from future terrorist attacks," the Baltimore County lawmaker said.
Ruppersberger traveled in a delegation that included leaders of the House and Senate intelligence committees. Their principal goal, he said, was to make sure that U.S. intelligence personnel in Afghanistan have the resources they need, particularly as they prepare for a larger role when U.S. combat troops leave in two years.
The delegation also met with Karzai and with Marine Gen. John R. Allen, the commander of NATO forces in the country.
The visit came after several incidents this year enflamed tensions between the U.S. and Afghanistan. These included an Internet video that appeared to show Marines urinating on Taliban corpses, the burning of the Quran at the U.S. air base at Bagram and the killing of 16 Afghan villagers, allegedly by an Army sergeant.
The Quran burning sparked several days of violent protests and attacks on international forces, apparently including the killing of Maryland National Guard Maj. Robert J. Marchanti II of Baltimore County. He was shot to death inside a secure ministry building in Kabul.
Ruppersberger said U.S. and Afghan leaders remain on the same page.
"Remember, this is a war zone — has been for a long time," he said. "Whenever there's an incident, it's serious, it impacts on groups of people. But what we learned, in our conversation with Karzai, and also with General Allen, is our relationship with the Afghan security forces is very strong and very positive.
"That's the key to making sure that the terrorist organizations and the Taliban do not take control of the country and allow them again to have an open area where they can plan attacks against the United States."
Ruppersberger expressed concern that Pakistan could become such an area. He said that "some of the Pakistani military and intelligence have relationships with those people who are fighting us."
Taliban fighters killed 14 Pakistani soldiers in a key militant sanctuary along the Afghan border, officials said Monday.
The killings in Miran Shah, the main town in the North Waziristan tribal area, highlighted the challenges confronting the Pakistani military in the border region. The area is used by the country's fiercest enemy, the Pakistani Taliban, and by Afghan and Pakistani militants believed to be close to the government who are battling U.S. forces in Afghanistan.
The U.S. has repeatedly demanded that Pakistan launch an offensive in North Waziristan, especially against the so-called Haqqani network. Pakistan has promised to do so, but says its forces are stretched too thin fighting the Pakistani Taliban in other areas.
"Something has to be done, and it's in the offing," Pakistan Lt. Gen. Khalid Rabbani told the Associated Press on Monday. "North Waziristan is the only place left" that hasn't been the target of an operation, he said.
In Kabul, Whittington, the Maryland Guard general, directs the training and development of the Afghan army and national police. He said the security forces have grown from 270,000 in January 2011 to 340,000, and should hit the target of 350,000 this fall, ahead of schedule.
He said several developments indicate a growing strength within the Afghan forces: rising literacy rates among the soldiers, declining attrition, an increase in the number of Afghans leading the training, and the growing number of military doctors, nurses, police officers and logistics specialists.
"Their warrior culture translates to a good fighting force," Whittington said. "And now they're focused on not only the fighting piece of it but also the education of their warriors."
Since the attacks on Marchanti and other U.S. troops, the Afghan army and the interior ministry have increased training and vigilance to identify possible threats from within their ranks, an aide to Whittington said.
The security forces also have instituted a new eight-step vetting process that requires recruits to have a valid and verifiable identification card, a letter of endorsement or recommendation from their village elders, and a criminal background check.
Maryland National Guard Lt. Col. Charles Blomquist said the incidents "certainly … had an impact on how we conduct our business, our operations here."
"We stay vigilant, we rely a great deal on the training that we've received, and frankly the Afghans have also done the same," said Blomquist, who in civilian life is a prosecutor in Baltimore. "While it's maybe caused some slight delays on some things, I think overall we understand that there's perhaps a bigger mission that we need to focus on."
More than 3,100 Maryland National Guard members have served in Afghanistan since Sept. 11, 2001, some on multiple tours. Four have been killed.
In Kandahar, members of the 1297th Combat Sustainment Support Battalion — known as Task Force Raven — are nearing the end of year-long deployment receiving, organizing and shipping equipment through insurgent-infested territory to troops on the front lines in southern and western Afghanistan.
When what commanders say was unintentional mishandling of the Qurans at Bagram drew violent protests, troops were ordered to undergo cultural sensitivity training.
Spec. Louis Resto, a human resources specialist with the 1297th, doesn't handle the Quran in the course of his work. But he said it wouldn't have occurred to him that burning the book would offend anyone.
"It was a surprise to me," he said.
Lt. Col. Wheedon Gallagher said the incident did not affect the unit's mission — or the relationship with Afghan translators and truck drivers.
Blomquist, in Kabul, is on his second deployment to Afghanistan. He was in Kandahar in 2004 and 2005, and has seen progress since then.
"Here in Kabul, you have a very large metropolitan city with a very vibrant economy," he said. "There are traffic jams just as you would find in any other large capital city. There are people out on the streets, there's commerce going on. …
"I'm an optimistic person by nature, and I see that there has been progress. I would like to think that our involvement here is leading to a better life for the Afghans."
The Associated Press contributed to this article.