WASHINGTON (AP) — The Pentagon has begun sending additional troops to Afghanistan to carry out President Donald Trump's new war strategy, which will stick to his predecessor's approach of supporting the Afghans' fight against the Taliban rather than doing the fighting for them, Defense Secretary Jim Mattis said Thursday.

"Yes, I've signed orders, but it's not complete," Mattis told reporters in an impromptu news conference at the Pentagon.

He would not say how many additional troops are deploying or what their exact roles will be. Trump's decision to deepen the American military commitment was...