In every administration, Republican or Democratic, it has been consistent United States policy to provide military aid to other nations only for defensive purposes. The logic of that policy is unassailable. The US is not in the business of promoting aggression, its own or others', but of forestalling it. It therefore comes as something of a surprise to hear sounds from the Reagan administration that, if Egypt attacked Libya, it would consider giving Egyptian forces US military protection from the Soviet Union.
Attack Libya? We are not unmindful of the war of nerves going on between the unpredictable Colonel Qaddafi and his Egyptian neighbor. But we can think of nothing worse for the US than to be seen as encouraging a preemptive attack on Libya, or any other nation for that matter. Such a move would be folly - putting the US on the side of aggression, playing into Qaddafi's hands, and inviting Soviet meddling. In any reasonable diplomatic stance, the US would assure Cairo of aid in the event Libya attacked Egypt.
The administration's upside-down posture seems dictated by a desire to distance itself from previous Carter policy. Specifically, to show that the US ''stands by its friends,'' as it says, and does not desert them in times of trouble (i.e., the Shah of Iran). Of course the US wants to stand by its friends - but surely only when its friends are in the moral right and deserve support. Today's ally can become tomorrow's adversary or vice versa (witness China), and any experienced diplomat knows better than to lock a relationship in concrete, especially one with an authoritarian government.
Hinting at providing a military ''umbrella' for Egypt in case of an offensive war sends out the wrong signals. It invites ambiguities. Is Washington saying, then, that Israel has the right to use American-supplied planes for offensive raids into Lebanon? That is not an irrelevant question as talk grows of a resumption of hostilities in that war-torn land. The US has long been concerned about Israel's use of US military equipment for other than defensive purposes.
One other point might be made. It is all well and good to be talking about protecting friends in the Middle East from Soviet intervention. But it might be sensible to minimize such talk until the US has the capabilities for effective help. From what one reads, the exercise ''Bright Star''now underway in Egypt, Sudan, Somalia, and Oman - while it may be a good start toward developing a Rapid Deployment Force - shows the huge sealift and airlift deficiencies which exist if the ultimate objective is to stop Soviet penetration. Moreover, the states of the region themselves prefer a low-key US stance that does not publicize the American presence there.
State Department officials stress that no formal plans or agreements have been made for guarding Egypt should the latter pounce on Libya. Good. Nor should such even be considered. If the United States gives the impression, rightly or wrongly, that it thinks such an attack desirable or permissible, what credibility will it have as a defender of peace?