Kabul (AFP) - The Afghan Taliban launched their "spring offensive" Friday, heralding fresh fighting in the drawn-out conflict as embattled security forces struggle to recover from a devastating attack on a military base one week ago.
Operation Mansouri -- named after the group's former leader, killed in a US drone strike in 2016 -- will target foreign forces with "conventional attacks, guerrilla warfare, complex martyrdom attacks, insider attacks", an insurgent statement said.
"The enemy will be targeted, harassed, killed or captured until they abandon their last posts," it continued.
The annual spring offensive normally marks the start of the "fighting season", though this winter the Taliban continued to battle government forces, most successfully in last week's attack on the military base outside the northern city of Mazar-i-Sharif.
The massacre last Friday saw insurgents armed with guns and suicide bombs slaughter at least 135 young recruits, according to the official toll, though multiple sources have claimed it is much higher.
It is believed to be the deadliest by the Taliban on an Afghan military target since they were driven from power in 2001, and marked yet another psychological blow by the resurgent militants.
Already beset by killings, desertions, and struggles over leadership and morale, Afghan forces have been straining to beat back insurgents since US-led NATO troops ended their combat mission in December 2014.
They faced soaring casualties in 2016, up by 35 percent with 6,800 soldiers and police killed, according to a US watchdog.
With more than one third of Afghanistan outside of government control, civilians also continue to bear a heavy brunt, with thousands killed and wounded each year with children paying an increasingly disproportionate price, according to UN figures.
Afghanistan's Interior Ministry shrugged off the Taliban threats Friday, saying the offensive was "not something new".
"We will target, kill, defeat and suppress the Taliban... all across the country," acting ministry spokesman Najib Danish told AFP.
The Taliban statement claimed this year will be different, however, vowing a political approach in areas it controls that will focus on state-building and "establishing mechanisms for social justice and development".
Afghan and international officials have repeatedly called on the Taliban to disarm and join the political process, a call they have so far refused.
- 'Another tough year' -
The Taliban announcement comes days after Pentagon chief Jim Mattis visited Kabul as the Trump administration seeks to craft a new strategy in Afghanistan.
Mattis warned that 2017 would be "another tough year" for Afghan security forces, but would not be drawn on recent calls by the US commander of NATO forces in the country, General John Nicholson for "a few thousand" more troops to break the insurgency.
The Afghan conflict is the longest in US history -- US-led NATO troops have been at war there since 2001, after the ousting of the Taliban regime for refusing to hand over Osama bin Laden following the 9/11 attacks in the United States.
The US has around 8,400 troops in the country with about another 5,000 from NATO allies. They are largely conducting a training, advise and assist mission aimed at supporting Afghan forces.
Earlier this month, the American military dropped its largest non-nuclear bomb on Islamic State group hideouts in eastern Afghanistan, killing nearly a hundred militants, according to unverified figures from Afghan officials.
The bombing triggered global shockwaves, but was criticised by observers who questioned its use against a group that is that is not considered as big a threat as the Taliban.
Some analysts even argued the strike could boost the Taliban, who had been fighting a turf war with IS 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 the US is also paying for its continuing role in the conflict.
Last Friday's Taliban assault on the military base fuelled fears over insider attacks -- when Afghan soldiers and police turn their guns on their colleagues or on international troops -- have been a major problem during the war.
The attackers all carried valid passes to the base, security sources told AFP, and were dressed in Afghan army uniforms. The defence minister and army chief have resigned, and authorities have arrested at least 35 soldiers over the incident so far, ranked from foot soldier to colonel.