THE EGYPTIANS recently got wind that their outlaw neighbors in Soviet-aided Libya were planning some new nastiness and asked the United States for support. This was not the first such alarm in recent years, and although in the earlier cases nothing much had happened to Egypt or to its neighbor and close ally Sudan, American officials figured it was better to be safe than sorry. This appears to be how four of those super AWACS air reconnaissance planes showed up at Cairo West airfield and the aircraft carrier Nimitz steamed into international waters off the coast of Libya.

This time too nothing in the way of Libyan trans-border adventurism seems to have happened. Therein lies the cause of a certain amount of headshaking and wonderment, friendly as well as not so friendly, about whether there was any fire behind the smoke, or whether there was even any real smoke. The information so far made public is not conclusive. But given Libya's rich, full record of depredations against its neighbors and others, and given in particular Sudan's acute vulnerability because of its poverty, inadequate institutional base and resurgent ethnic factionalism, it made sense to offer a little timely, unprovocative and preemptive support. Even if there turned out to be no urgent need to deter Libya, it was not a bad idea to respond as requested in order to reassure Egypt and Sudan, good friends of the United States.

Some of the remarks President Reagan made at his news conference, and some of the administration's subsequent comments, suggested more than a little confusion and raised a certain question of how closely Mr. Reagan was tracking a matter that involved, after all, a show of force against the one country this administration has already used force against. American planes downed two Libyan planes that had challenged them in international air space over the Mediterranean in 1981.

It is possible, however, to get too tangled up in the details. The important point is that whatever Libya may have had in store for Sudan this time around, nothing happened. The United States made a restrained use of its military power and a couple of friendly states seem to have been able to relax as a result. American AWACS flights and carrier cruises are not the only security requirements in that corner of the Middle East. Egypt and Sudan have a strong claim on the United States for aid, military as well economic. Egypt, linked by American politics to Israel as far as aid goes, customarily does pretty well. Sudan, not so linked, tends to lose out. It seems too bad that any country so desperately poor should have to divert any of its international assistance to military purposes. There is no denying, however, its military needs.