President Bush gambled his final two years in office last night on the success of a new “Iraqi-led” plan to quell sectarian violence in Baghdad and tackle the gathering power of militias.

In a televised speech Mr Bush announced that he was deploying up to 22,000 extra US troops to Iraq as he acknowledged personal responsibility for past mistakes in a war that will inevitably define his political legacy, including failing to put enough forces on the ground.

The President’s 20-minute prime-time address warned the Government of Nouri al- Maliki that America’s patience and commitment are not unlimited, and promised that the new strategy “will change America’s course in Iraq, and help us succeed in the fight against terror”.

In place of his former optimism on Iraq, he offered a downbeat definition of success, saying: “Victory will not look like the ones our fathers and grandfathers achieved. There will be no surrender ceremony on the deck of a battleship.”

Mr Bush made plain that he had rejected the key components of what he called the “thoughtful recommendations” of last month’s independent Iraq Study Group report, which had urged him to start redeploying troops away from Iraq and embark on a new diplomatic offensive in the Middle East.

Although there was a nod in the direction of the report, with a pledge to increase the number of US troops embedded with the Iraqi security forces and an offer of a $1 billion (£500 million) jobs programme, Mr Bush signalled that there was no immediate prospect of re-engaging states such as Iran and Syria, whose influence in Iraq, he said, must be countered. Instead, he ech- oed earlier rhetoric about the war being the “decisive ideological struggle of our time”. He said that to “step back now would force a collapse of the Iraqi Government . . . [and] result in our troops being forced to stay in Iraq even longer”.

The increase in US troop levels, which will take the number of American servicemen in Iraq to almost 154,000, is designed to secure Baghdad, where 80 per cent of the sectarian violence takes place. The Iraqis will deploy three extra army brigades in the city, operating under a unified command structure and rules of engagement that are designed to ensure that they are unfettered by what Mr Bush called the “political or sectarian interference” that had contributed to the failure of previous initiatives.

The US will commit gradually five more brigades to the Iraqi capital and another 4,000 US Marines will be deployed in Anbar province, which Mr Bush said had turned into al-Qaeda’s “home base”.

Dressed in a sober dark suit and blue tie, Mr Bush emphasised repeatedly last night the leading role that the Iraqis would play in the new strategy and, in a telephone conversation yesterday morning, was apparently assured by the al-Maliki Government that it will take on the powerful Shia militias such as the Mahdi Army.

“Only the Iraqis can end the sectarian violence . . . America’s commitment is not open- ended,” Mr Bush said. “If the Iraqi Government does not follow through on its promises, it will lose the support of the American people — and it will lose the support of the Iraqi people. Now is the time to act.”

Promises made by the Shia-dominated Government include meeting a series of benchmarks, ranging from sharing oil revenues and bringing Sunnis into the political process to the more ambitious goal of taking responsibility for security in the whole country by November.

The failures and factionalism of the al-Maliki Government have been sources of growing frustration for the White House. But Mr Bush’s emphasis on the Iraqi leadership’s role in the new strategy will also give him some cover should it go the way of so many of his previous policies in the war.

Although Mr al-Maliki has announced a new security crackdown in Baghdad, there appears little appetite within his Government for a full-scale assault on the Mahdi Army. Leaders of the Mahdi Army have, nonetheless, ordered all men aged 15 to 45 in the largest Shia slum in Baghdad to register for “mandatory service”.

In Washington, Democrats voiced their opposition. Nancy Pelosi, the Speaker of the House of Representatives, has pledged to hold a vote on the troop increase. Some want to block the $5.6 billion of funding needed to pay for it.

Tony Blair remains hopeful that British forces will be withdrawn this year at the time that he leaves office. He told MPs yesterday that the situation in the south was “very different”, suggesting that Britain’s exit strategy would not be affected.

Significant reductions in British troop numbers this summer, however, are now being discounted. Senior diplomatic and defence sources told The Times that it would not be appropriate for Britain to halve its military presence from 7,000 to about 3,700 by the early summer, as expected, while Americans were boosting troop levels.

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