THE U.S. military said it carried out an airstrike yesterday against al Shabaab militants in Somalia, in the second such action this week. The Pentagon said the strike took place in the vicinity of Galmudug, Somalia, and emphasized that no U.S. forces were accompanying Somali troops during the operation. It came just three days after a similar U.S. strike targeting the al Qaeda-linked Islamist group, which is seeking to topple the Somali government and impose its strict interpretation of Islamic sharia law. "U.S. forces are authorized to conduct strikes in support of combatant commander designated partner forces under collective self-defense,"…