As much as 8400 U.S. troops still roam around in the country as part of the NATO-led Resolute Support training and advisory mission, as well as a separate counterterrorism mission.
The bombing aimed to erode IS's capabilities in Afghanistan, but it was also seen as a warning to the much bigger Taliban group. It sparked widespread anger and led to the resignations of the defence minister and the army chief of staff, along with a reshuffle of army corps commander, leaving security forces facing disarray as fear and suspicion grew that the militants had inside help.
They faced soaring casualties in 2016, up by 35 per cent with 6,800 soldiers and police killed, according to a U.S. watchdog.
The attackers carried valid passes to the base, security sources said, and were dressed in Afghan army uniforms.
Taliban spokesman Zabihullah Mujahid announced the launch of the offensive in an emailed statement that boasted of Taliban control over more than half of the country, referring to a February report issued by Washington's special inspector general for Afghan reconstruction.
The Taliban on Friday announced the start of their annual rebel offensive in Afghanistan, a media report said.
"We will target, kill, defeat and suppress the Taliban. all across the country", acting ministry spokesman Najib Danish told AFP.
Apart from the strategic tapping of the area, the Taliban would also mull over mustering political support and so according to the spokesperson, institutions would be built in areas under their control, establishing what can be termed "social justice and development" mechanisms.
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Navy Lt. Chris Donlon, a spokesman for USA forces in Afghanistan confirmed that the incident happened close to Achin and near where US aircraft dropped a massive 22,000-pound bomb, called a GBU-43, two weeks ago. They are largely conducting a training, advise and assist mission aimed at supporting Afghan forces.
The deaths mark the third time this year that a member of the US military has died in combat in Afghanistan.
The Taliban has extended its territorial control in Afghanistan since the withdrawal of global combat troops in 2014 and inflicted heavy casualties on Afghan forces.
As well as the Taliban, Afghanistan is also battling an emerging local affiliate of the Islamic State group known as Islamic State in Khorasan, which is an ancient name for a region that once included Afghanistan, Iran and parts of Central Asia.
The deaths come just days after Defense Secretary James Mattis visited Afghanistan to assess the security situation and advance deliberations about the Trump administration's strategy for the United States' longest war.
Some analysts even argued the strike could boost the Taleban, who had been fighting a turf war with ISIS in Nangarhar province near the border with Pakistan, where the bomb was dropped.
Two US troops were killed Wednesday while fighting IS militants near the blast-site, the Pentagon has said, highlighting the price of its continuing role in the conflict.