General Sir Richard Dannatt, the chief of the General Staff, told the Times of London that part of the 12th Mechanised Brigade, which had been training for deployment to Iraq but were later stood down, had now been "earmarked for Afghanistan."

The report came as US President Barack Obama announced a major escalation of the war in Afghanistan and its further extension into Pakistan. Echoing the Bush administration's military "surge" in Iraq, Obama outlined plans to send 4,000 more troops to Afghanistan on top of the 17,000 additional forces already committed, and signalled Washington's intent to aggressively expand the war across the border into Pakistan.

Currently the UK has some 8,000 troops in Afghanistan. Although Dannatt said that there were no plans to send a whole brigade of 4,000 troops, and defence sources described the 2,000 as "the uppermost ceiling," the statements were couched in vague terms.

A Ministry of Defence source said later that any decision would be based on advice from the military. "If the clear advice...is that we need more people to keep our troops safe, we will make a judgment based on this," he said.

The equivocation is due to concern among the high command of "military overstretch." In the same Times interview, Dannatt made it clear that although a number of military options were being considered to boost Britain's presence in Afghanistan, sending an extra brigade would put too much strain on British forces. "If we were to send another 4,000...there would be a risk of replicating the pressures on the Army that we are trying to avoid," he said.

He agreed with Air Chief Marshal Sir Jock Stirrup, the chief of the Defence Staff, who said recently that he could not support any plan to engage in "a one-for-one" movement to Afghanistan, under which the 4,000 troops being withdrawn from Iraq by July 31 would be transferred to Helmand Province.

"Improving security in Afghanistan will be dictated by having more boots on the ground," said Dannatt. "I don't mind whether the boots will be American, British or Afghan." He added that Afghanistan was going to be "a marathon campaign, not a sprint."

Despite the cautious language, Dannatt's statement and other comments make clear that the British government is fully committed to a significant stepping up of the US-led intervention in South and Central Asia and is attempting to pressure its European counterparts to do the same.

The Observer newspaper reported March 29 on the British government's declaration of full backing for a US-led military offensive inside Pakistan, as UK ministers confirmed the country was now "part of a single campaign" alongside Afghanistan.

Defence Secretary John Hutton said Britain supported targeting Pakistan-based Taliban and Al Qaeda positions and urged Europe to begin offering assistance to eradicate insurgents in the tribal regions bordering Afghanistan. Making clear Britain's readiness to participate in the widening regional conflict, Hutton said military objectives in the region must now have "an equal focus on both countries."

"We remain, as we have been on many occasions in this past century, grateful to the United States for the leadership that she has shown time and again since 2001 in rooting out extremism and terrorism in Afghanistan," he continued. "But Europe must do more, and it is in our interest to do more."

"In Europe," he said, "we can no longer offload the tough questions about how we deal effectively with AQ [Al Qaeda] and the Taliban in Pakistan to the US. The political burden of dealing with the Pakistan side of the border must be shared. And there are many European countries with strong ties to Pakistan that can more effectively share that burden with America."

Hutton condemned "the massive leadership imbalance" between Europe and the US in NATO, adding, "It's an imbalance set to grow in the coming months as America commits vastly more resources of every kind to the mission in Afghanistan."

Britain's targeting of Pakistan was further underscored last week when Prime Minister Gordon Brown outlined the government's renewed national security strategy. Citing Al Qaeda in Pakistan as the greatest security threat facing the UK, it claimed that two-thirds of terror plots uncovered by British intelligence agencies have a Pakistani connection.

The implications of British military involvement in Pakistan are major. As the former colonial power in the region, the UK has long historical ties with Pakistan and is home to the second largest Pakistani diaspora of over 900,000 people.

More broadly, US actions in Afghanistan and Pakistan, supported by Britain, represent a threat to the entire region. It is difficult to imagine how a military conflict on Pakistani territory proper would not entangle India—the other nuclear power in the region. Under conditions of spiralling regional tensions, the short border that Afghanistan shares with China may also become a flash point, drawing in the Beijing regime, while Russia, as a regional power, would be compelled to intervene, raising the prospect of a far wider war.

The new focus on Pakistan is set to dominate NATO's 60th anniversary summit in Strasbourg later this week, in which Britain and the US will again attempt to pressure the other NATO members—particularly Germany, France and Spain—for additional military forces. But senior NATO diplomatic sources leaking to the press said that no meaningful offers were expected from any alliance member apart from Britain. Italy and Poland are planning to send small reinforcements, but only during the campaign for the Afghan presidential election, due to be held on August 20.

NATO has so far committed 32,000 troops to Afghanistan, with Germany deploying 3,640, France 2,780 and Spain 780.

The killing of Pakistani civilians by air-strikes carried out by unmanned CIA aircraft is increasing popular anger in Pakistan against the US and the Pakistani government's collaboration with Washington's war. However, US officials made clear at the weekend that attacks along Pakistan's western frontier will continue, amid speculation that coalition ground units may begin crossing into Pakistan's borderlands at some point. A Pentagon spokesman, Lieutenant Colonel Mark Wright, told the Observer that the US had already offered to launch "joint military operations" with Pakistan's Frontier Corps in the tribal areas.