Suicide bombers killed at least 18 people in Afghanistan on Saturday during Chuck Hagel’s first visit as U.S. secretary of defense, highlighting the extreme violence that continues to plague the country more than a decade after the American invasion.

The bomber was riding a bicycle outside of the Ministry of Defense in Kabul when the blast hit, according to media reports, killing nine civilians. Hagel was reportedly nowhere near the scene of the explosion.

The Afghan Taliban claimed responsibility for the attack, saying in a statement that it “was a kind of message” for Hagel, Reuters reports.

Another suicide bomber attacked a police checkpoint in the eastern province of Khost, killing a policeman and eight civilians, according to The Associated Press. Most of the dead were reportedly children.

Hagel, who arrived in Afghanistan Friday, is set to meet with President Hamid Karzai. The visit coincides with the passing of a deadline set by Karzai, who has ordered the American military to curtail its activities. Karzai U.S. ordered special forces to leave the province of Wardak after accusing them of overseeing the torture and killings of people in the area.

Coalition forces have denied involvement in any of those abuses.

Hagel, speaking to U.S. troops on Friday before the bombings, said the war is still “a dangerous and difficult mission.”

“We are still at war, and many of you will continue to experience the ugly reality of combat and the heat of battle,” he said. “But the goal we have established — to have Afghans assume full responsibility for security by the end of 2014 — is clear and achievable.”

As defense secretary, Hagel is responsible for overseeing the drawdown of American troops in preparation for 2014, when NATO will transfer security control to Afghan forces.