On an Afghan ridge 7,800 feet above sea level, about four miles from Pakistan, stands a mud-brick fortress nicknamed the Alamo. It is officially dubbed Firebase Lilley, and it is a nerve center in the covert war against the Taliban and al-Qaeda.

The CIA has relied on Lilley, part of a constellation of agency bases across Afghanistan, as a hub to train and deploy a well-armed 3,000-member Afghan paramilitary force collectively known as Counterterrorism Pursuit Teams. In addition to being used for surveillance, raids and combat operations in Afghanistan, the teams are crucial to the United States' secret war in Pakistan, according to current and former U.S. officials.

The existence of the teams is disclosed in "Obama's Wars," a forthcoming book by longtime Washington Post journalist Bob Woodward. But, more broadly, interviews with sources familiar with the CIA's operations, as well as a review of the database of 76,000 classified U.S. military field reports posted last month by the Web site WikiLeaks, reveal an agency that has a significantly larger covert paramilitary presence in Afghanistan and Pakistan than previously known.

The operations are particularly sensitive in Pakistan, a refuge for senior Taliban and al-Qaeda leaders where U.S. units are officially prohibited from conducting missions.

The WikiLeaks reports, which cover the escalation of the Afghan insurgency from 2004 until the end of 2009, include many descriptions of the activities of the "OGA" and "Afghan OGA" forces. OGA, which stands for "other government agency," is generally used as a reference to the CIA.

In clipped and coded language, the field logs provide glimpses into the kinds of operations undertaken by the CIA and its Afghan paramilitary units along the Pakistani border. In addition to accounts of snatch-and-grab operations targeting insurgent leaders, the logs contain casualtyreports from battles with the Taliban, summaries of electronic intercepts of enemy communications and hints of the heavy firepower at the CIA's disposal.

The CIA declined to comment on the Counterterrorism Pursuit Teams. A Pakistani official said the government will not comment on Woodward's book until after it is released.

A U.S. official familiar with the operations, speaking on the condition of anonymity, described the teams as "one of the best Afghan fighting forces," adding that they have made "major contributions to stability and security."

The official said that the teams' primary mission is to improve security in Afghanistan and that they do not engage in "lethal action" when crossing into Pakistan. Their cross-border missions are "designed exclusively for intelligence collection," the official said.

In addition to Firebase Lilley, in Paktika province, the WikiLeaks logs reveal the existence of an "OGA compound"at Forward Operating Base Orgun-E, another U.S. military installation in Paktika.

The field reports show that casualties are common for Afghan paramilitary forces training and operating there.

On Oct. 6, 2009, for example, an "OGA-trained" fighter was ambushed near Orgun-E while off duty, according to one log; he was treated on the base for gunshot wounds to the face, lower leg and hand.