Newly uncovered "rules of engagement" show the U.S. military gave elite units broad authority more than three years ago to pursue suspected terrorists into Pakistan, with no mention of telling the Pakistanis in advance.

The documents obtained by The Associated Press offer a detailed glimpse at what Army Rangers and other terrorist-hunting units were authorized to do earlier in the war on terror. And interviews with military officials suggest some of those same guidelines have remained in place, such as the right to "hot pursuit" across the border.

Pakistan, a key U.S. partner in the aftermath of the Sept. 11 attacks, has long viewed such incursions as a threat to its sovereignty. Islamabad protested loudly this month when Democratic presidential candidate Sen. Barack Obama pledged to grant U.S. forces the authority to unilaterally penetrate Pakistan in the hunt for terrorist leaders.

Washington repeated assurances it would consult before any such incursions.

But summaries of the rules of engagement on the Afghanistan-Pakistan border in April 2004 say chasing Al Qaeda leaders across the frontier was fair game.

One summary states that "Entry into PAK authorized for" the following reasons:

--"Hot pursuit" of Al Qaeda, Taliban and terrorist command-and-control targets "from AFG into Pakistan (must be continuous and uninterrupted)."

--If the head of U.S. Central Command, which oversees American forces in the Middle East and Central Asia, approved direct action "against The Big 3," listed as Usama bin Laden; his deputy, Ayman al-Zawahiri; and Taliban supreme leader Mullah Omar. The three are still believed to be hiding in the border region.

--If the Defense secretary approved such an incursion.

Other grounds for incursions into Pakistan, according to this summary, were "personnel recovery," including rescuing troops after the downing of aircraft; and troops "in contact with" the enemy, meaning under fire.

As for "geographic limits," the memo states: "General rule: penetrate no deeper than 10 km," or 6.2 miles.

Told of the guidelines, Pakistani military spokesman Maj. Gen. Waheed Arshad said, "This is all nonsense. Pakistan never allowed the coalition forces to enter into our territory while chasing militants. There was no such agreement, there was no such understanding."

Pentagon spokesman Lt. Col. Todd Vician said this week he could not comment. "As a policy we don't talk about rules of engagement, certainly not about current rules in place for any operations in Afghanistan, Iraq or any other operation," he said.

The 2004 documents were included among 1,100 pages of investigative documents generated by the Army's probe into the death of NFL player-turned-Ranger Pat Tillman, whose platoon was operating in the region at the time.

E-mail exchanges between Ranger officers in the documents make no mention of a requirement to inform Pakistan in advance of strikes into that country.

However, one summary mentions a chain of required notifications, which resulted in Pakistan being apprised -- apparently after the fact. One rule says "joint task force commander must inform CENTCOM immediately" and ensure the "Mil Liaison team" in Islamabad was notified.

Operations officers had a hot line to that liaison office, which would in turn inform Pakistani officials, according to a U.S. officer who served in the region and is knowledgable about operations within Afghanistan during that mid-2004 period. On some occasions, the officer said, Pakistanis would detect ground or air incursions and request explanations from the Americans, who would open inquiries.

Interviews with officers in the field, and the public statements of top U.S. commanders, indicate similar guidelines remain in place today.

At a hearing of the Senate Armed Services Committee in March, Sen. Bill Nelson, D-Fla., asked Army Lt. Gen. Douglas Lute, "Do we have to have the approval of the Pakistani government in hot pursuit across the border?"

No, Lute replied. If U.S. forces spot so much as a "hostile intent" against them and chase the threat toward the border, "then we have all the authorities we need to pursue, either with fires or on the ground, across the border," he said.

Even a surveillance report of enemy fighters setting up a rocket and pointing it west into Afghanistan is enough to trigger a unilateral military response, said Lute, then the chief operations officer for the Joint Chiefs of Staff and now President Bush's deputy national security adviser -- the "war czar" on Iraq and Afghanistan.

Capt. Scott Horrigan, a former company commander at Camp Tillman, an outpost about a mile inside Afghanistan's eastern Paktika province, told the AP earlier this year that rules of engagement allowed U.S. forces on the ground to travel up to a kilometer, a little more than half a mile, into Pakistani territory if they had "eyes on" insurgents, not just terrorist leaders.

Horrigan said that pursuit would require the approval of Pakistani authorities or Horrigan's brigade commander. It wasn't clear whether the brigade commander was required to consult with Pakistani officials before such an incursion. Through a spokesman at Fort Drum, where he is currently stationed, Horrigan declined to comment this week.

Horrigan also said in the earlier interview that U.S. aircraft could penetrate up to 10 kilometers into Pakistan, but must seek permission first. And he said his soldiers had fired from Afghanistan into Pakistan "two or three times." With fire coming from Pakistan, "usually I can fire back," he said, citing "an inherent right to self-defense."

Lt. Col. David Accetta, spokesman for U.S. troops in Afghanistan, said last week he could not talk about rules of engagement along the Pakistan border. He did say, after an AP reporter informed him of Horrigan's comments, that the rules haven't changed since January, when Horrigan spoke.

A high-ranking Ranger officer who has served in Afghanistan and is familiar with the current rules of engagement said that if he found himself "in contact" with the enemy at the border, he would feel authorized to chase them into Pakistan. He spoke on condition of anonymity because of the high sensitivity of the U.S.-Pakistan relationship.

Occasionally, there have been signs of American operations in the Pakistani frontier.

In January 2006, tribal elders told the AP that U.S. helicopters had launched an attack on remote Saidgi village, about three miles from the Afghan border in Pakistan's lawless North Waziristan tribal region.

A tribal leader, Momin Khan, said the Americans took away five tribesmen. The Muslim cleric whose home was attacked was not there, but an explosion had killed eight people and wounded nine.

The U.S. military denied involvement, and Pakistan's chief Army spokesman said he couldn't confirm the raid.

A week later, the CIA purportedly sent a Predator drone from Afghanistan into Pakistan, unsuccessfully firing missiles at al-Zawahri. The attack missed bin Laden's deputy but reportedly killed four other al-Qaida leaders -- although that information was never verified -- and 13 villagers. Pakistan officially condemned the attack and said it had no advance notice.

In recent weeks, top Bush administration officials have staked out sometimes varying positions on the matter of penetrating Pakistani's borders.

On Aug. 5, Defense Secretary Robert Gates was cautious in describing how U.S. officials would handle an incursion. "I think we would not act without telling (Pakistani President Gen. Pervez Musharraf) what we were planning to do," he said on NBC's "Meet the Press."

That was far more tentative than what White House homeland security adviser Frances Townsend said last month when asked on Fox News why the U.S. wasn't sending special operations forces and drones into Pakistan.

"Well, just because we don't speak about things publicly doesn't mean we're not doing many of the things you're talking about," Townsend said. She didn't elaborate.

On Aug. 5 at Camp David with Afghan President Hamid Karzai, Bush wouldn't say whether he would consult with Pakistan before ordering U.S. forces to act inside that country. "With real actionable intelligence, we will get the job done," Bush said, without elaborating.