KABUL - The top US military commander in Afghanistan said on Thursday President Donald Trump's new strategy is a sign of a long-term commitment to what is already America's longest war and called on Taliban insurgents to agree to peace talks.

“The Taliban cannot win on the battlefield, it’s time for them to join the peace process ,” General John Nicholson told reporters in Kabul. “We will not fail in Afghanistan, our national security depends on that as well.”

He claimed that President Donald Trump’s new strategy is a sign of a long-term commitment to what is already America’s longest war.

Nicholson said new advisers from the United States and NATO coalition allies would increase the training missions, including at specialised military schools and expanding the Afghan air force and special forces.

He also praised Trump’s decision not to impose “arbitrary” deadlines on the American mission in Afghanistan. “This policy announcement … is proof of our continued commitment,” he said.

The US general vowed to annihilate the Islamic State and crush what remains of Al-Qaeda after President Trump announced a renewed effort in the war that has dragged on for nearly 16 years.

He told reporters that additional US troops will further train Afghan forces and promised more air support. Nicholson also urged the Taliban to pursue diplomacy and said that Afghan commandos and special forces were strong.