“After 18 months, our troops will begin to come home,” he added, seeking to reassure Americans the plan does not mean a war without end, and rejecting the comparison with the Vietnam War as a “false reading of history.” The United States now has 71,000 US troops in Afghanistan, while about 40 nations have about 42,000 there. The first US Marines could be in place by Christmas, four months after General Stanley McChrystal, commander of US and NATO forces in Afghanistan, warned the eight year-old war could be lost without more manpower.

“The clarity, commitment and resolve outlined in the president’s address are critical steps towards bringing security to Afghanistan and eliminating terrorist safe havens that threaten regional and global security,” McChrystal said.

Obama said attacks against the United States are “being plotted as I speak,” and warned he would go after Osama bin Laden militants operating in Somalia, Yemen or further afield if necessary. He ramped up pressure on European allies for more troops, saying they were also threatened by Afghan-based terrorism. NATO Secretary General Anders Fogh Rasmussen said US allies “will send at least 5,000 soldiers to this operation, and possibly a few more thousand on top of it.” Britain has already said it will send an extra 500 troops and Poland said it could send up to 600 next year. But France, Germany and other key contributors are reluctant to increase their presence.

Britain currently has about 9,500 troops in the international force, Germany 4,300 and France 3,750. Many European leaders want the Afghan government to assume more responsibility for security and development. Following a strategy review, Obama rolled out new political approaches to Afghanistan and Pakistan.

He warned the Afghan government of President Hamid Karzai, that the days of a US “blank check” were over and demanded a drive against corruption. The same “cancer” of extremism that had torn at Afghanistan was also hurting Pakistan, Obama said, crediting Islamabad with an unprecedented effort to combat home-grown extremism.

The Afghan government was “satisfied” with the new strategy, said senior foreign ministry adviser Daud Muradyan.

India on Wednesday warily backed President Barack Obama’s surge of 30,000 extra US soldiers for Afghanistan, and pledged to push ahead with aid for the reconstruction of the war-ravaged country. India, which does not have troops in the ISAF coalition, has provided more than one billion dollars in humanitarian and development assistance to Afghanistan since the Taliban were ousted in 2001. “We are dealing with a different part of the solution than is the US military,” junior foreign minister Shashi Tharoor told reporters. “We are contributing through development, we are building roads, schools hospitals, clinics and this is the sort of assistance we can provide. Others are taking the security burden.” Obama phoned Indian PM on Tuesday to explain his proposals.

President Barack Obama’s strategy of bringing a quick end to the war in Afghanistan with 30,000 more troops hinges on training and equipping enough Afghan forces to secure the country themselves.

But analysts say that proper recruitment and training of an army and police able to hold the Taliban at bay are likely to take far longer than the 18-month period outlined by Obama before foreign troops start coming home.

Obama’s top commander in Afghanistan, who had requested tens of thousands of extra troops to avoid defeat, said he now had “the resources to accomplish our task” and that his “main focus” will be to build up Afghan security forces.

General Stanley McChrystal, who expects to command more than 140,000 NATO and US troops once reinforcements arrive, vowed to transfer responsibility to Afghan security forces “as rapidly as conditions allow”.

President Hamid Karzai has pledged to take responsibility for Afghan security within the next five years.

But analysts warn it could take up to another decade to build up the necessary numbers in a country riddled with corruption, where more than 70 per cent of the population is illiterate and the Taliban are expanding.