The United States is being hamstrung in its battle against the terrorist threat by its involvement in Iraq, leading Democrats claimed today.

Members of the House Armed Services committee seized on comments made to a Senate hearing yesterday by the US Ambassador to Iraq as evidence that the White House had prioritised the wrong conflict.

In his testimony Ryan Crocker had admitted that if he was forced to choose which would most benefit US security – defeating all al-Qaeda in Afghanistan or in Iraq – he would opt for the former.

Today those remarks were hurled back at him in exchanges over the 160,000-strong US force currently in Iraq.

“Protecting this nation from direct attack is job number one, yet our allocation of forces does not match this imperative,” Representative Ike Skelton, the Democratic committee chairman, said.

“The effort in Iraq, however important, is putting at risk our ability to decisively defeat those most likely to attack us,” he added.

General David Petraeus, the top US commander in Iraq, was asked how he thought Congress should respond to a recent statement by Admiral Fallon, his counterpart in Afghanistan, that he needed 2,000 extra troops “today.”

While the general would not be drawn on whether troops should be redeployed, he said Congress would have to “weigh how much more it can resource.”

Under pressure, he acknowledged that he did not know who had determined, or when, that Iraq was the central front in the war on terror.

The general also agreed with a recent statement by General Cody, the US Army’s Vice Chief of Staff, that the strategic reserve was the “lowest he’d seen in his time.” There was “no question” that this was the case, he said.

Security in Afghanistan has seen a rapid deterioration in recent months and President Bush recently appealed to leaders at a recent Nato summit to step up their commitments to the violence-ravaged country.

Lord Ashdown, the former UN envoy to Bosnia whose appointment to the equivalent position in Afghanistan was blocked by President Hamid Karzai, warned last week that the Nato-led alliance was “getting pretty close” to losing control of the country altogether.

But at today’s hearing, General Petraeus and Ambassador Crocker were at pains to stress the consequences of reducing troop levels in Iraq, saying such a move could allow al-Qaeda and Shia militia groups to regroup.

In their war report, they said that there had been both political and security progress in Iraq under last year’s military surge but that advances remained “fragile and reversible”.

General Petraeus recommended that the US halt force reductions once a level of 140,000 troops had been reached in July and undertake a 45 day period of “consolidation and evaluation”.

An indeterminate period of “assessment” would then ensue, during which further reductions might recommended as and when conditions allowed.

Though Democrats claimed the plan amounted to an “open-ended pause," the general today expressed optimism that improving security in four or five areas of the country might allow more troops to come home.

President Bush is expected to endorse the recommendation during a key speech on Iraq tomorrow, meaning the incoming president can expect to take office in January with over 100,000 troops still stationed in the country.

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