Al-Qaida showed on 9/11 the enormous damage it can do armed only with laptop computers, Internet accounts, credit cards and box cutters. Just think how lethal the terror network could be if it gets its hands on the vast Saudi arsenal of American-made jets, missiles and — don’t forget — AWACS early-warning planes.

As the House of Saud wobbles on the brink of disaster, that’s a scenario very much on the minds of American policymakers.

Such an arsenal, so close to Israel’s borders and to American interests in the region, would pose a serious strategic threat in al-Qaida’s hands.

Saudi Arabia is engaged in a civil war in which shootouts between security forces and well-armed terrorists are regular occurrences. Another American worker was murdered there over the weekend and one taken hostage by jihadis seeking to overthrow the regime. The victims are part of the expatriate force the Saudis depend on for maintaining their American-supplied arsenal and the nation’s critical oil industry.

Individuals are considered soft targets, compared with the heavily protected oil facilities, but their technical expertise is also essential to the kingdom’s welfare. Driving them out and discouraging others from taking their place will further destabilize the shaky regime.

“The spreading disruptions in the kingdom coupled with the fact that the Saudis appear to be at a loss as to how to deal with them puts the United States in a position where it may have to send in troops to protect the oil infrastructure,” said Gilbert Kahn, a political science professor at Kean University.

The resulting chaos would produce significant repercussions, especially for an American economy struggling to recover and a military already spread too thinly.

A direct attack on the oil facilities could boomerang for al-Qaida, however, and create popular resentment when ordinary Saudis see the source of their livelihood threatened. But there is little sympathy for the foreign infidels, thanks to years of preaching intolerance and hatred in the government-controlled media, mosques and schools — and thanks to longstanding American support for a corrupt and repressive regime.

The true enemies of the House of Saud are not the Zionists, as the ruling princes insist, but their fellow Saudis.

Earlier this month, Saudi officials held a Washington news conference to announce they’re closing down several charities funneling money to terrorist groups. Terrorism experts are skeptical since the Saudis have made and broken such promises for years.

Part of the problem is how Saudis define terrorism. Attacks on the kingdom, yes; attacks on Israelis, no, that’s legitimate resistance to the Zionist occupation.

Taking them seriously became tougher when the ruling prince blamed the Jews for attacks inside the kingdom by homegrown extremists who want to topple him. Crown Prince Abdullah declared it is “95 percent” certain that “Zionist hands are behind” those attacks. That bigotry and delusional thinking was reinforced by his spokesman, Adel al Jubeir, explaining that his prince meant the regime’s critics (his euphemism for Zionists) have the “same objectives” as Osama bin Laden.

Compounding the insult was an assistant secretary of state, Anthony Wayne, who stood next to al Jubeir and didn’t disagree.

And that’s a big part of the problem.

Successive American administrations have propped up the corrupt royal family and refused to take them to task for their support for terrorists, the incitement of hatred that is standard fare in their schools and media or their corruption.

If the House of Saud didn’t rule over the world’s largest oil reserves, no one would mourn its passing. But the Saudi regime, as inept and venal as it is, has one advantage: It beats the most likely alternative.

Some analysts contend al-Qaida is going after soft targets instead of the oil infrastructure because it hopes to take ownership of that vital resource as the new rulers in a revived Islamic caliphate.

And with the oil, they want the great arsenal of weapons the House of Saud has built with longstanding American assistance.

If this column sounds like “I told you so,” that’s because it is. Those of us who challenged the Reagan administration’s sales of AWACS, planes, missiles and many other advanced weapons systems throughout the 1980s argued that the Saudis would not use them to defend themselves because they’d rely on us to do the job, and that they could fall into the hands of radicals likely to turn them on American and Israeli targets.

We also didn’t buy the argument that the sales would encourage Saudi engagement in the peace process with Israel, or to use its influence against Palestinian terrorism and help keep oil production up.

History has proven us right.

The administration and its supporters, however, were right on one count — the sales were good for business. But not for the American consumers who wound up paying for all that hardware at the gas pump.

Now, as the kingdom teeters, the same intelligence and diplomatic circles that once assured us that the Shah of Iran was stable and his American arsenal safe are saying the same about the Saudis.

That really makes me worry. Once again, America is supporting a repressive regime menaced by religious extremists who can threaten our basic interests by getting their hands on the oil pumps and the triggers.

If the House of Saud lacks the courage to play a responsible role in the war against terror, perhaps we should help them step aside and make way for those who will.

Douglas M. Bloomfield is a Washington, D.C.-based political consultant who was formerly chief legislative lobbyist for AIPAC.