President Barack Obama has sided with U.S. military and Defense Department officials in rejecting a proposal by the U.S. ambassador to Pakistan for a U.S. apology for last weekend’s attack on two Pakistani border posts, and approving an investigation into the attack that won’t be completed until Dec. 23 at the earliest.

The White House and the military bloc are gambling that the lengthy investigation into the attack that killed 25 Pakistani troops will defuse popular Pakistani anger and that final report will allow the Obama administration to return to a more aggressive policy toward Pakistan in 2012.

But the course Obama has chosen is likely to further aggravate the anti-U.S. sentiment in Pakistan that has boiled over in response to the violation of Pakistani sovereignty and unprecedented number of deaths of Pakistani troops. U.S. diplomats in Pakistan and State Department officials are seriously concerned that the rejection of any acknowledgement of U.S. responsibility for nearly three weeks will push Pakistan further toward a potentially irreversible break in relations with the United States.

Pakistan has vowed to close "permanently" the U.S.-NATO logistics routes through which more than half of the supplies needed for the war in Afghanistan must pass. Despite the development of an alternative set of routes through Central Asian republics, that closure will seriously constrain the U.S. ability to wage war in Afghanistan within four to six weeks, according to Washington Post columnist David Ignatius, who usually reflects the latest thinking of Pentagon and CIA officials.

Although Washington hopes that decision will be reversed in the coming weeks, some U.S. officials warn that the closure could harden under popular political pressure.

Serious concern about rapidly rising anti-U.S. sentiment forcing the hand of the Pakistani government led the U.S. ambassador to Pakistan, Cameron Munter, to urge the White House to move quickly to assuage Pakistani anger, according to the New York Times and the CNN security blog "Security Clearance."

Munter reportedly told a group of White House officials that if the United States has evidence that Pakistani troops had actually fired at U.S. troops first, it should provide it to Pakistan, but that if it has evidence that U.S. forces were at fault, the White House should issue a formal apology in order to prevent far more serious deterioration of relations.

Defense Department officials argued, however, that no statement on the attack should be issued by the White House until the formal investigation is completed, and that the expression of condolences by the White House press secretary and cabinet officials was sufficient until then, according to a report in the New York Times first published Nov. 30.

The investigation launched by CENTCOM commander Gen. James N. Mattis is to be completed and a report submitted by Dec. 23, but the letter from Mattis states that the officer in charge may request additional time to complete it.

At the daily State Department briefing by spokesman Mark Toner Friday, a reporter referred to "concern expressed by U.S. officials in this building…that the window is rapidly closing for the United States to come up with some kind of explanation for the Pakistanis."

The Defense Department argument that the United States can keep the Pakistani government and population waiting for more than three weeks for the results of the investigation is based in part on the longstanding assumption that the Pakistani military will be forced to accommodate U.S. interests, because of its dependence on U.S. assistance.

Decades of patron-client relations between the Pakistani military and their U.S. military and CIA counterparts have created a widespread belief in the military and CIA that Pakistan is too dependent on the United States for assistance to cut loose completely from U.S. policy.

A Dec. 1 column by the Washington Post‘s Ignatius shows that the notion of Pakistan is client state remains intact among Pentagon officials.

Ignatius suggested that the Pakistani military will soon have to wake up from its gestures of opposition to U.S. policy – especially the cutoff of NATO supplies for Afghanistan.

"Continued Pakistani reprisals make sense only [if] Islamabad is heading toward a real and lasting break with Washington," he wrote, adding, "I don’t get the sense that’s what Pakistan’s leaders really want."

So the Pakistanis "will need to figure out how to climb down the hill," he wrote, "now that they have forcefully planted the flag."

The justification for the military and DOD officials to oppose the admission of responsibility for those deaths and to express regret for it is not based on a conviction that U.S. troops were innocent in the Nov. 26 attack. The Nov. 30 New York Times report said DOD officials "did not deny some American culpability in the episode…."

That private admission suggests that the real reason for rejecting an apology is that it would shift the focus of media attention away from the Pakistani policy of allowing insurgents to have safe havens in Pakistan from which to carry out operations in Afghanistan.

U.S. military and Defense Department officials desperately need to make the case that Pakistani complicity in Taliban insurgent attacks across the border in Afghanistan is the primary obstacle to the success of the 10-year U.S.-NATO war in Afghanistan.

That interest can only be served if the investigation ordered by CENTCOM concludes that there is no reason for the United States to apologize, because of the threat to U.S. troops from insurgents who have been protected by the Pakistani army.

The investigation would have to give credibility to the claim by the U.S. Special Operations Forces (SOF) unit and its Afghan counterpart that they pursued the insurgents who attacked them across the border to a location close to, if not inside, an encampment that turned out to be a Pakistani border post.

A series of news media stories in the days after the incident reported just such accounts from members of the SOF commando unit, but the Pakistani army command provided details that refuted it. The U.S. military has denied that the attack on the border posts was deliberate, but it has also acknowledged privately to the New York Times that U.S. troops were culpable in the deaths of the Pakistani troops.

The U.S. military investigation is supposed to be open to Pakistani participation, though not as an equal partner. But Pentagon spokesman George Little confirmed Friday that Pakistan has elected not to participate in it.

Maj. Gen. Ashfaq Nadeem, the Pakistani Army’s director general of military operations, has pointed to earlier "joint investigations" of U.S. violations of Pakistani sovereignty as having "come to naught." He referred to "joint investigations" with the International Security Assistance Force (ISAF) into the three U.S.-NATO attacks on Pakistani troops on Jun. 10, 2008, Dec. 30, 2010 and Jul. 17, 2011.

The reports generated by those inquiries "give a version not based on facts as we know them," Nadeem said.

The appointment of Brig. Gen. Stephen Clark to carry out the investigation of the attack on the Pakistani border posts raises yet another issue: whether the investigation will hold the SOF unit involved and the helicopter pilots attached to it fully accountable.

Clark has spent virtually his entire military career in the Air Force Special Operations Command.

The helicopter pilots who made crucial decisions during the assault on the border posts were almost certainly affiliated with the Air Force Special Operations Command.

Even more than other branches of the military, Special Operations Forces officers are known for protecting other SOF personnel against any legal challenge. When he was commander of ISAF in 2010, SOF veteran Gen. Stanley A. McChrystal used two separate investigations to deflect charges that an SOF unit had covered up the killings of two pregnant women in a February 2010 night raid gone bad.