The strike hit a checkpoint run by militants between the southern towns of Zinjibar and Jaar late Monday. Militants believed to be close to Al-Qaeda have seized control of both towns in recent months.

Security across Yemen has broken down amid a five-month uprising seeking to oust longtime President Ali Abdullah Saleh. The United States worries that Al-Qaeda could exploit chaos in Yemen to increase operations there.

The security official spoke on condition of anonymity because he was not authorized to speak to the media.