The bomb that targeted a U.S. embassy vehicle in Beirut on Tuesday was the first attack on American interests there since the 1980s.  The blast killed three people and wounded at least 16, and almost all of the casualties were Lebanese bystanders.  Lebanese media suspect the attack was timed to send a message to President Bush as he wrapped up his Middle East tour.  Analysts say given the chaotic security situation in Lebanon, it is possible that the bombers will never be found.  VOA's Challiss McDonough has more from our Middle East bureau in Cairo.

Firefighters try to extinguish a burning car at the site of an explosion in Beirut, Lebanon, 15 Jan. 2008

U.S. and Lebanese investigators spent the day scouring the site of the bombing for evidence of who might have carried it out and how. 

In the aftermath of the blast, Lebanese officials noted that although the bomb almost certainly targeted an American Embassy vehicle, all but one of the casualties were Lebanese civilians.  They said they view the bombing as an attack on Lebanon's stability.

It was the first attack on U.S. interests in Lebanon since the 1980s, and it came as President Bush was touring the Middle East.

Youth and Sports Minister Ahmed Fatfat said some people are trying to consider the attack as a message for the Americans regarding Mr. Bush's visit to the region.  But he said the U.S. president did not go to Lebanon, and so he considers that the attack targeted Lebanon itself.

Some local newspapers wrote that the attack was an effort to derail Arab League efforts to end Lebanon's political crisis, which has left the country without a president since November.

Traveling with the president in Saudi Arabia, Secretary of State Condoleezza Rice said the United States will not be intimidated by a terrorist act.

Condoleezza Rice in Riyadh

"The United States will of course not be deterred in its efforts to help the Lebanese people, to help the democratic forces in Lebanon, to help Lebanon resist foreign interference in their affairs, and to uphold the many security council resolutions passed on behalf of a stable and democratic Lebanon," she said.

Analysts say given the extreme security measures taken by U.S. diplomats in Lebanon, it is clear that this attack was carefully planned and executed.  Timor Goksel was the longtime U.N. spokesman in Lebanon and is now teaching political science at the American University of Beirut. 

"So this was a specific anti-American attack, but as to the motive and who's behind it, I don't know if you'll ever find out," he said.

Looking at the bombing in a regional context, he said there is a long list of extremist groups that could be behind such an attack.

"Look at what's happening in the Middle East," he noted.  "Three days ago, Americans announced they killed 60 al-Qaida guys in Iraq.  Then you have all these people getting killed non-stop in Gaza.  All these groups have organic or non-organic connections here. They have supporters, sympathizers.  Some have extensions. So the list of usual suspects is rather long this time."

Most analysts believe the attack on the U.S. embassy vehicle cannot be separated from the overall security situation in Lebanon.  The country has seen a series of high-level political assassinations over the last three years.  A U.N. vehicle was bombed just a few days ago, and a top Lebanese Army general was killed last month.

Goksel points out that nobody has been arrested for any of the killings.

"And so this is almost like a free environment to come and do what you want because the security system is very fragile and very weak," he added.  "And nobody is afraid of getting caught.  You know, Lebanon is unusual in the sense that it's the most liberal and most free country in this part of the world.  But here it is free for all at the moment, and it seems that whoever is doing it - and we have enough candidates - they seem to have no fear of ever getting caught."

The U.S. embassy has placed further restrictions on the movement of its staff in Lebanon and warned American civilians to "avoid popular gathering spots" and stay on high alert.

The State Department says a joint FBI-State Department team is going to Lebanon to investigate the blast.