Ashraf Ghani thanked the US for supporting "the joint struggle against the threat of terrorism".

Donald Trump has committed the US Army to the open-ended conflict, despite previously advocating its withdrawal.

The Taliban responded by saying it would make Afghanistan a "graveyard" for US forces.

Mr Trump offered few details on the plan, but singled out Pakistan for criticism for offering "safe havens" to extremists.

Pakistani officials reject claims the country uses some militants as a tool of state policy.

What is the new strategy?

President Trump warned a hasty US withdrawal from Afghanistan would leave a vacuum for terrorists to fill and said he had decided to keep troops there to "fight to win" to avoid the mistakes made in Iraq.

He said his new approach would be more pragmatic and based on conditions on the ground rather than idealistic and time-based, and would switch from nation building to "killing terrorists".

But he refused to get drawn on how many extra troops, if any, would be deployed and gave no timeline for ending the US presence in the country.

Washington is expected to send up to 4,000 additional troops, but Mr Trump did not comment on this.

In June, he told the Department of Defense to decide on troop levels.

Visiting Baghdad on Tuesday, Defence Secretary Jim Mattis said he would wait for a plan from the chairman of the Joint Chiefs of Staff based on the president's South Asia strategy before deciding.

"It may or may not be the number that is bandied about," he told reporters.

Mr Trump also, for the first time, left the door open for an eventual peace deal with the Taliban, saying: "Someday, after an effective military effort, perhaps it will be possible to have a political settlement that includes elements of the Taliban in Afghanistan."

However, Mr Trump said there would be an escalation in the battle against groups like al-Qaeda and so-called Islamic State.

Meanwhile, Mr Trump made it clear he expects his existing allies - including India - to support him in his new strategy, and urged them to raise their countries' contributions "in line with our own".