Taliban kill 21 at start of Afghan spring fighting
Also Monday, rockets hit inside the grounds of the Kabul international airport but caused no damage. Rockets also struck the NATO base at Bagram, just north of the Afghan capital, causing minor damage, the alliance said.
This year's Taliban spring offensive comes at a sensitive time, against the backdrop of a key presidential election. Militants have also stepped up terror attacks to sow insecurity and weaken the government as international forces prepare to withdraw from the country by the end of this year.
Fewer than 30,000 U.S. troops remain on the ground in Afghanistan, the lowest number since the 2001 invasion. Last summer, Afghan security forces took full responsibility for the country's defense, making this Taliban spring offensive an important gauge of how well they will face insurgent attacks once international forces are gone.