Militants have staged two deadly suicide attacks to mark the first full day of US Defence Secretary Chuck Hagel's visit to Afghanistan, a fresh reminder that insurgents continue to fight and challenges remain as the US-led Nato force hands over the country's security to the Afghans.
A suicide bomber on a bicycle struck outside the Afghan Defence Ministry in Kabul, and about half an hour later another suicide bomber attacked a police checkpoint in Khost city, the capital of Khost province in eastern Afghanistan.
Nine people were killed in the bombing at the ministry, and an Afghan policeman and eight civilians, who were mostly children, died in the blast in Khost, said provincial spokesman Baryalai Wakman.
"This attack was a message to him," Taliban spokesman Zabiullah Mujahid said of Mr Hagel, in an email to reporters about the defence ministry attack.
Mr Hagel was nowhere near the blasts, but heard them across the city. He told reporters travelling with him that he was not sure what it was when he heard the explosion.
"We're in a war zone. I've been in war, so shouldn't be surprised when a bomb goes off or there's an explosion," said Mr Hagel, a Vietnam War veteran.
Asked what his message to the Taliban would be, he said that the US was going to continue to work with its allies to ensure that the Afghan people have the ability to develop their own country and democracy.
Hagel's first visit to Kabul as Pentagon chief comes as the US and Afghanistan grapple with a number of disputes, from the aborted handover of a main detention facility - cancelled at the last minute as a deal for the transfer broke down - to Afghan president Hamid Karzai's demand that US special operations forces withdraw from Wardak province just outside Kabul over allegations of abuse.
The prison transfer, originally scheduled for 2009, has been repeatedly delayed because of disputes between the US and Afghan governments about whether all detainees should have the right to a trial and who will have the ultimate authority over the release of prisoners the US considers a threat.
The Afghan government has maintained that it needs full control over which prisoners are released as a matter of national sovereignty. The issue has threatened to undermine ongoing negotiations for a bilateral security agreement that would govern the presence of US forces in Afghanistan after the current combat mission ends in 2014.