The powerful blast shook windows and rattled doors around the eastern half of Beirut today. it happened right at the beginning of rush hour when roads are packed with commuters. Radio stations announced the blast as black smoke billowed over the capitol. The embassy vehicle was traveling north on a road that parallels the Mediterranean coast, presumably towards the US Embassy located on an isolated hillside north of the capitol. US Embassy personnel are under strict security protocol here and travel only in armored cars and with body guards. That's because the US lost hundreds of officials and US troops in attacks here during Lebanon's 1975-1990 war. Today, the US is deeply involved in Lebanon's current political crisis. It's backing the government of Prime Minister Fuad Sinoira against the Syrian-backed, Hezbollah-led opposition. The US uses diplomatic pressure on Syria and its allies here but it also supplied the Lebanese Army with ammunition and vehicles during its four-month battle against the Al Qaeda-inspired Islamic group Fatah al Islam. Just last week the leader of that group threatened to attack again in Lebanon so there is a long list of suspects for today's attack. This Lebanese man who lives near the blast says he's not surprised the US got hit here but by who he wouldn't guess, �They have a very huge amount of enemies worldwide so of course it's for political reasons. They say the US is backing someone here and so on but clear evidence, I don't know.� Today's bombing may be a jolt for the US in Lebanon, but it's nothing new for the Lebanese. This is one of more than a dozen bombings and assassinations that have racked the Lebanese capitol since the 2005 assassination of former Prime Minister Rafik Hariri.