On the eve of the dropping a massive 21,600-pound bomb in Afghanistan targeting Islamic State (ISIS) fighters from Iraq and Syria hiding in an underground network in that country, Trump announced on Wednesday he is sending National Security Adviser Lt. Gen. H.R. McMaster there to assess the situation for troops on the ground.

Trump made the announcement during a press conference on Wednesday with North Atlantic Trade Organization (NATO) Secretary General Jans Stoltenberg, as reported by Military Times.

The U.S. has been at war in Afghanistan since 2001, after the September 11 attacks by radical Islamic terrorists on U.S. soil that killed 3,000 people.

The U.S. has some 8,400 troops in Afghanistan, with an additional 5,000 deployed from NATO allies, Business Insider reported. Army Gen. John Nicholson told Congress in February he needed a “few thousand” more troops in order to break what he called a “stalemate” with the Taliban terrorists.

“Of about 400 districts in Afghanistan, the Taliban controls, contests, or influences 171 of them, according to the Special Inspector General for Afghanistan Reconstruction,” Business Insider reported.

Voice of America (VOA) reported last month that the U.S. military in Afghanistan is ratcheting up the offense against the growing Islamic State branch in the Afghanistan-Pakistan region.

“Since he took office, President Donald Trump has been ramping up military operations against both the Islamic State, also known as ISIS and ISIL, as well as al-Qaeda, particularly in Yemen,” VOA reported.

“We stand confident that the new U.S. administration under President Trump will remain strategically engaged and continue its support,” Afghanistan’s Foreign Minister Salahuddin Rabbani said at an appearance at the Atlantic Council in Washington.

American Navy Capt. Bill Salvin, the spokesperson and director of public affairs for the U.S./NATO-led coalition in Kabul, told VOA that “our goal in 2017 is to defeat ISIS-K in Afghanistan.”

Green Beret Staff Sgt. Mark De Alencar, 37, of Edgewood, Maryland, was killed earlier this month fighting jihadists in the eastern part of Afghanistan near the Pakistani border.

The fatality brings the total number of U.S. military deaths since the war started more than 15 years ago to at least 2,249, most of which occurred under former President Barack Obama’s watch, according to Pentagon data.

This marks the first time the bomb, known as the GBU-43, or “Massive Ordnance Air Blast,” (MOAB) was used in combat. Its yield is 11 tons of TNT and has been nicknamed the “Mother of All Bombs.”

It remains uncertain so far if the bombing was planned under the Obama administration or the Trump administration.

Pentagon spokesman Adam Stump said the plan has been in place for a “few months,” and that the weapon had been in Afghanistan for “some time.”

The final test of the MOAB took place on March 11, 2003 and was delivered into theater on April 1, 2003.