WASHINGTON - U.S. Defence Secretary Robert Gates and Adm. Michael Mullen of the Joint Chiefs of Staff (JCS) remained tight-lipped about the contents of a confidential report on the future of U.S. involvement in Afghanistan in a wide-ranging Pentagon briefing on Thursday.

U.S. Secretary of Defense Robert Gates takes questions from the news media during a press conference at the Pentagon in Arlington, Virginia. (AFP/Getty Images/File/Chip Somodevilla) The report, authored by U.S. Afghanistan commander General Stanley McChrystal, is expected to lay the groundwork for a recommendation that President Barack Obama authorise an increase in combat troop numbers to help stabilise the deteriorating situation in Afghanistan. McChrystal has previously called the situation on the ground "serious" yet salvageable.

The report is due to be discussed with the president some time next week as a matter of urgency resulting from the growing public dissatisfaction with the conduct and progress of the war.

The press conference, however, offered little illumination on the potential surge in troops, rumoured to be as many as 25,000, as Gates and Mullen evaded reporters' questions probing the actual contents of McChrystal's report.

Gates denied that control of the war was slipping through the administration's fingers while acknowledging indications that U.S. public opinion is fading fast.

Mullen said that the situation necessitated a sense of urgency and that there was "a limited time for us to show this [new] approach is working."

According to a CBS poll this week, 41 percent are now calling for a reduction in troop levels - an eight point rise since April. The number who believe that the U.S. should commit additional troops has correspondingly declined 14 points, leaving only 25 percent who believe a higher commitment is necessary.

President Obama himself is facing additional criticism as now only a minority of citizens - 48 percent - approve of his handling of the counterinsurgency.

At the press briefing, reporters suggested that the lack of a clearly defined missions and criteria for success were central to the disillusionment felt by the U.S. public. In response, Gates said that he believed President Obama had been "crystal clear" on the objectives of the war in a recent speech to the Veterans of Foreign Wars.

Gates said it was important to remember that the attacks of Sep. 11, 2001 directly emanated from Afghanistan - which provided, and continues to provide, a worldwide base for al Qaeda and a safe haven for terrorism.

"We're in Afghanistan less for nation building and more to give Afghanistan the capacity to oppose al Qaeda... and sustain this over a long period of time," Gates said.

The administration's criteria for success, Gates said, would be "the Afghan national security forces assuming a greater role in protecting their own territory" as U.S. forces progressively receded into the background.

Gates said President Obama recognised that the problem is a regional issue not limited by national boundaries - the reversal of the deteriorating situation in Afghanistan depends heavily on stability in the neighbouring Pakistan with which it shares a long and porous border rife with extremist groups.

Gates also addressed his previous worries that the "footprint" of the U.S. forces - the impact and influence they have on the native population - would become a problematic issue akin to the situation senior commanders identified in Iraq. Gates said it remained a major concern, but was confident that McChrystal's new approach in which the protection of civilians is paramount would mitigate the impact of any new influx of troops.

Gates cautioned drawing comparisons between the military "surge" approach implemented in Iraq and the situation on the ground in Afghanistan due to fundamental differences between the two societies - primarily, the lack of a strong central state apparatus in Afghanistan at any point during its history.

"It is a real mistake to compare Iraq and Afghanistan. I see that a lot. There are real limits to analogies between them," he said.

Even some on the right are turning against the war, testifying to the deepening cracks within the political establishment.

In an opinion piece in the Washington Post this Tuesday, conservative columnist George Will argued that the U.S. should abandon nation-building efforts in Afghanistan and began withdrawing its troops.

"Forces should be substantially reduced to serve a comprehensively revised policy: America should do only what can be done from offshore, using intelligence, drones, cruise missiles, airstrikes and small, potent Special Forces units, concentrating on the porous, 1,500 border with Pakistan, a nation that actually matters," Will wrote.

Gates dismissed Will's recommendations as "unrealistic", citing the impossibility of counterinsurgency programmes without any soldiers on the ground: "The notion that you can conduct a purely counterterrorist campaign, and do it from a distance, simply does not accord with reality," Gates said.

Mullen agreed, adding: "There is no way you can defeat al Qaeda remotely... You can't do it from offshore."

The problems facing U.S. efforts to stabilise the region have been exacerbated by the controversial Aug. 20 elections, which have been undermined by accusations of voter fraud and intimidation on a mass scale.

Over 600 irregularities submitted to the Independent Election Commission have been classified as serious, the BBC reports, and regulations prevent the results of the election being announced until all allegations have been fully investigated. Many estimate this will delay the official outcome until the end of September.

A successful democratic election is crucial to the multinational effort to establish a viable central government in the region, which in turn is considered essential in the drive to purge the country of Taliban and al Qaeda influence.