The Taliban has announced the start of the spring offensive, signalling plans to step up attacks as the weather warms across Afghanistan, making both travel and fighting easier.
The statement on Saturday comes toward the end of the deadliest month for combat deaths this year.
The militant group's leadership vowed that "every possible tactic will be utilised in order to detain or inflict heavy casualties on the foreign transgressors."
Hand over: Afghan forces are gradually taking over security responsibility as US-led international forces gradually scale down. Photo: AFP
It said that will include more so-called insider attacks by members of the Afghan security forces against their colleagues or foreign troops.
Such attacks threaten the strength of the Afghan forces as they work to take over responsibility from international forces. The latest one occurred in March, when a member of Afghanistan's government-backed militia program shot and killed five of his colleagues in Badghis province in northwest Afghanistan.
In a sign of Taliban's determination to replace Afghanistan's government with one promoting a stricter interpretation of Islamic law, they named their new offensive after a legendary Muslim military commander, Khalid ibn al-Walid. Also known as "the Drawn Sword of God," he was a companion of Islam's Prophet Mohammed.
US-backed efforts to try to reconcile the Islamic militant movement with the Afghan government have so far failed.
Insurgents intensified attacks this spring as they try to position themselves for power ahead of national elections and the planned withdrawal of most US and other foreign combat troops by the end of 2014.
April has already been the worst month for combat deaths so far this year. According to an Associated Press tally, 257 people - including civilians, Afghan security forces and foreign troops - have been killed in violence around the nation. During that time 217 insurgents have died.
Last year during the month of April, 179 civilians, foreign troops and Afghan security forces were killed and 268 insurgents.
Still, the top US commander in Kabul, Marine General Joseph Dunford, said on Wednesday that the security situation has improved across the country.
"As the traditional fighting season begins, the insurgency will confront a combined " Afghan force of 350,000 soldiers and police, he said.
"The insurgency can no longer use the justification that it is fighting foreign occupiers - that message rings hollow," Dunford said in a statement.