A group calling itself the Islamic Struggle Organization claimed responsibility for a bomb blast at the US Embassy here which killed at least 28 people, including six US marines. The same Islamic group claimed responsibility for a grenade attack that wounded five US marines last month.
In Washington, President Reagan denounced the bombing as a vicious terrorist attack, but said it would not deter the United States from continuing its search for peace in the region.
Some observers said the blast was likely to hurt the standing of the US in the region. If Washington cannot protect its own embassy in Beirut, Lebanese may well ask, how can its peacekeeping force - even an expanded one - guarantee that Lebanon will not fall again into its old patterns of sectarian violence?
The success of the terrorists is also likely to make US congressmen leery of committing more troops to the multinational peacekeeping force already stationed in Beirut. The US force has been subjected to several terrorist attacks, and a US marine was killed last year when he accidentally set off a previously unexploded bomb.