JALALABAD, Afghanistan (AP) — The Taliban unleashed a wave of attacks that killed 21 people around the country, making a show of strength to start the spring fighting season. The annual surge in violence poses a new test for Afghan security forces, who for the first time will face it largely on their own as international combat forces prepare to withdraw.

Spring each year brings an escalation in fighting in Afghanistan with the end of snowy winter weather, which hampers movement. The melting of the snows opens up mountain passes allowing militant forces to move in from refuges in neighboring Pakistan.