US Homeland Security chief Janet Napolitano assured probing senators that the Secret Service agent misconduct in Colombia never jeopardised President Barack Obama's safety.

Napolitano yesterday pled

US homeland security secretary Janet Napolitano arrived in Afghanistan for talks with Afghan officials and to spend the New Year's holiday with American troops, her office said.

A statement issued from Washington said Napolitano arrived early Friday in Kabul with US customs and border security officials to help provide civilian assistance to local officials.