Top officials resign in Afghanistan after Taliban kills more than 140 soldiers

US Defense Secretary Jim Mattis arrived in Afghanistan on an unannounced visit Monday, hours after his Afghan counterpart resigned over a deadly Taliban attack that triggered anger and left the embattled army in disarray.

Afghanistan's President Ashraf Ghani (R) arrives to visit the victims of April 21's attack on an army headquarters, in Mazar-i-Sharif, northern Afghanistan April 22, 2017.

At least 130 Afghans were killed and the country's army chief and defense minister resigned.

Mattis is visiting as Afghans are looking to President Ghani to announce a four-year security plan for the country in the coming weeks.

German federal prosecutors say they have charged a 17-year-old Afghan citizen over allegations he joined the Taliban and participated in attacks against security forces. The Taliban claimed responsibility, saying it sent 10 militants to avenge recent killings of senior Taliban leaders.

But the official said that the attack was too sophisticated and "calculated" to have been conducted by other branches of the Taliban.

Mattis' visit followed a Taliban raid on an Afghan base last week that killed over 100 soldiers and military personnel.

A suicide auto bomb attack reportedly took place near a military camp in Afghanistan's southeastern Khost province on 24 April.

The exact toll from the assault remains unclear.

The attack triggered global shockwaves, with some condemning the use of Afghanistan as what they called a testing ground for the weapon, and against a militant group that is not considered as big a threat as the Taliban.

Habibi had come under intense pressure from Afghan lawmakers following an Islamic State attack on a Kabul military hospital in March.

The attack comes just days after a group of U.S. Marines deployed to Afghanistan's tumultuous Helmand Province for the first time since the end of America's combat mission in 2014.

Former President Barack Obama had wanted to reduce the number of USA troops in Afghanistan before he left office.

The statement said that at this meeting, discussions centered on the current situation in the country and on the reinforcement and development of security forces. Some of them detonated explosives among hundreds of unarmed troops who were emerging from Friday Prayer, while others went on a rampage gunning down soldiers, majority new recruits in training. They know the Afghans there, and the level of training they'll provide is more sophisticated because of that past experience.