U.S. Defense Secretary James Mattis said yesterday he would present options on Afghanistan to President Donald Trump "very soon," adding the strategy would take a regional approach rather than looking at the war-torn country in isolation.

The situation in Afghanistan, which U.S. military officials acknowledge is in a stalemate almost 16 years since the war started, has deteriorated in recent months.

A truck-bomb explosion in Kabul last month killed more than 150 people, making it the deadliest attack in the Afghan capital since the ouster of the Taliban in 2001.

In some cases, Afghan security forces have been forced to abandon more scattered and rural bases, and the government can claim to control or influence only 57 percent of the country, according to U.S. military estimates earlier this year.

"We are taking a regional approach to this," Mattis told the House Armed Services Committee. "We will take that forward to the president for a decision very soon."

Mattis said a request by General John Nicholson, the head of U.S. and international forces in Afghanistan, for additional troops would mostly be made up of troops who would train, advise and assist Afghan forces, potentially putting them with Afghan forces at the brigade level.

"It's a fundamental change to how we bring our, what I would call our real superiority, in terms of air support," Mattis said.

At the same hearing, Chairman of the Joint Chiefs of Staff Joseph Dunford said he had gone to Mattis and Trump with "some options that might be considered" in order to help improve the security situation in Afghanistan.

Reuters reported in late April that Trump's administration was carrying out a review of Afghanistan and conversations were revolving around sending between 3,000 and 5,000 U.S. and coalition troops there.

Deliberations include giving more authorities to forces on the ground and taking more aggressive action against Taliban fighters.

Some U.S. officials questioned the benefit of sending more troops to Afghanistan because any politically palatable number would not be enough to turn the tide, much less create stability and security. To date, more than 2,300 Americans have been killed and over 17,000 wounded.

On Saturday, three U.S. soldiers were killed when an Afghan soldier opened fire on them in eastern Afghanistan.