WATCH: Mattis says Afghan forces fully engaged for first time

WASHINGTON — Defense Secretary Jim Mattis says Afghanistan security forces are fully engaged in offensive military operations for the first time during the 16-year-old war.

Defense Secretary Jim Mattis and Chairman of the Joint Chiefs of Staff Joseph Dunford are scheduled to testify before the Senate Armed Services Committee at 10 a.m. ET today. Watch their remarks in the player above.

During congressional testimony Tuesday, Mattis says the Afghan forces are suffering fewer casualties as they continue to improve.

Mattis says more than 3,000 additional U.S. troops are being sent to Afghanistan to reinforce the roughly 8,400 American forces currently stationed there.

President Donald Trump announced in August a plan to end America’s longest war and eliminate a rising extremist threat in Afghanistan.

Sen. John McCain of Arizona, the chairman of the Armed Services Committee, lectured Mattis and Gen. Joseph Dunford at the opening of the hearing. McCain says the Trump administration has failed to inform Congress of the details of the strategy spelled out by Trump.

READ MORE: Pentagon admits U.S. has more troops in Afghanistan than previously reported