MORE THAN a week later, the suicide car-bomb that blasted the U.S. embassy in Lebanon continues to send a message far beyond, the rattled windows of Beirut. It has become clear that our government is incapable of learning from the past, and that the present Administration's efforts against terrorism have done little more than provide a speech topic for high officials.

Despite President Reagan's assertions to the contrary, the lapses in security which let a crazed fanatic gun his bomb-laden van to the front entrance of the embassy remain nothing short of shocking.

Eight weeks ago, the threats against American personnel were still coming, and the fledgling Lebanese government had yet to prove itself able to guarantee order. But the State Department decided anyway that the newly relocated embassy was somehow safe enough, and withdrew the 80-man Marine contingent armed with the heavy weapons that could have stopped the car-terrorist.

In fact, the Marines were withdrawn long before the embassy had been made secure. Officials knew that shatter-resistant windows, reinforced blast walls, earthen berms, and even simple gates were crucial to containing terrorist attacks. But they allowed the embassy personnel to move in before protective devices had been completely installed. Only a few easily negotiated concrete barriers stood between the killer-car and the embassy.

Security procedures were so lax that the terrorist van was already far past local Phalangist militiamen before they realized something was wrong and started to shoot. Only the chance presence of the British ambassador and his bodyguards, who shot the driver before he could enter the building's garage, saved the embassy from total destruction.

THE LACK OF attention to security extended right to Washington. A Defense Intelligence. Agency report showing that the new embassy was unsafe was not distributed to senior State Department officials until after the bombing--even though the report had been completed at least a week before.

Even now, days after the bombing, diplomatic security in Lebanon remains inadequate. The old embassy, which still has U.S. personnel and government papers, is guarded by sleeping Lebanese soldiers. An alleyway leading to its front entrance has been left totally open, according to news reports.

Under ordinary Lebanese circumstances, such lapses would border on the criminally negligent. Yet the car-attack was not the first, but the third such strike against American installations in Beirut--following the unforgottably tragic destruction of the U.S. embassy 17 months ago and the more recent Marine compound bombing which killed 241 Americans.

It is unconscionable that those incidents haven't led to supertight security. As Robert S. Dillon, former ambassador to Lebanon, said of the car attack: "When I saw the TV this morning, I asked, 'How could it happen again?'"

The administration, eager to cover itself as the Presidential election draws near, has tried to explain away the terrorist success, shrugging its shoulders and blaming the Carter administration, even comparing the delays in security construction to problems people have when they redo their kitchens. Only infilitration of terrorist sects can stop their attacks, Reagan said, and suggested two days ago that the real fault lies with "the near destruction of our intelligence capability" in the years before his administration.

One would hope that Reagan understands the difference between kitchens and embassies, particularly when those embassies have been bombed repeatedly. Fatalism will not prevent terrorists from striking again. Neither will blaming Carter, who actually increased the intelligence budget after it had been slashed under Republican administrations.

In any case, the quality of intelligence really isn't the issue--any high school student who watches the news could tell you that Lebanon is a dangerous place. The real issue is the lack of interdepartmental coordination, inattention to security detail, and general absence of common sense revealed by the most recent attack. Couldn't just a few good Marines armed with some sort of anti-tank weapon have prevented the suicide car from getting anywhere near the embassy?

NOT ONLY must our government beef up security, it needs also to address the question of retaliation, because an undeterred criminal will strike again. We have yet to deter or punish anyone, despite our brave words that we would avenge our dead. After last year's Marine bombing, the U.S.A promised to "respond to this criminal act." Nothing ever happened, even though Secretary of Defense Caspar W. Weinberger '38 later said the bombing was executed with the "sponsorship, knowledge, and authority of the Syrian government."

Of course, one must hesitate before striking out to avoid injuring innocents. And in the case of Islamic Holy War, which has claimed responsibility for the past three attacks on American installations, it has apparently been impossible to ascertain its exact nature and membership. But, according to The New York Times, intelligence officials worldwide almost all agree that the Holy War gang has major links to the Iranian and Syrian governments, which have the most to gain from humiliating the America. Surely the United States has the capability to make life unpleasant for these two regimes, as they have so often done for us.

Without concrete proof of guilt, both world opinion and Americans' own moral sense would make overt military action. Yet increasing support to their enemies (such as Iraq, which is bogged down in war with Iran) would finally make Iran and Syria understand the costs of sponsoring or aiding terrorist attacks. Certainly, such action needs to be weighed against our other geopolitical interests in the area. But doing nothing would only show weakness and invite more attacks against Americans.

Another step the U.S. could take to show true concern about stopping terrorism would be to limit its own terrorist acts in Central America. The CIA's unsecret secret war against the Nicaraguan regime, a war that has led us to mine Nicaraguan harbors, sponsor cross-border contra raids, and wink at Americans illegally selling their services as mercenaries against the Sandinistas, has made a mockery of our efforts to get other nations to support our efforts for international coordination against terrorism.

The Administration justifies its own terrorism mainly by arguing that the Nicaraguan regime, because of its quasi-totalitarian nature, is illegitamate and a threat to our security. But if we are to preach the principle of national self-determination and the need to ensure civilized behavior, we cannot do it arbitrarily. We cannot mine harbors in one section of the world because we dislike one nation's regime, and then express outrage when our embassies are bombed in a different regime someone else happens to dislike.

As the attack on our embassy makes abundantly clear, we sorely need an effective and consistent approach to combatting terrorism, from the nitty-gritty of improving diplomatic security all the way to punishing those responsible for terrorism and even restraining ourselves from engaging in terrorist attacks. Such a policy may seem difficult, costly, and at times apparently against our short-term interest. But in a world of proliferating destructive technology, where fanatics seem ever ready to sacrifice their lives for some obscure cause, we may have no choice.