A camel in Managua

THE camel seems to be a principal element of President Reagan's Nicaragua policy. No, not anything like the French Saharan Camel Corps used in Algeria in the 19th century, or the 3 million humped beasts used in World War I.

The camel upon which Mr. Reagan seems to be relying is rather a creature of metaphor: the proverbial camel outside the Arab's tent. It sticks its nose into the tent, and then its head, and so on -- pleading implicitly at each stage only for a bit more protection against the cold desert night. Before the Arab knows what has happened, the camel has taken over the tent and he is out on his ear.

Hitherto the administration's expressed justifications for financial support of the contras have been, first, that support for contras would stem the alleged arms flow into El Salvador, and later, that such aid would help extract some ill-defined ``concessions'' from the leftist Sandinistas ruling in Managua.

But in an interview with the Mexican newspaper Excelsior, released this week, the President said that unless the Nicaraguan government accepted democracy, the ``only alternative'' for the rebels there would be for them ``to have their way and take over.''

By this time the camel is in the tent up to its shoulders.

Now, the content of the President's comments came as a surprise to no one; opponents of contra aid have felt all along that the President's real goal has been to oust the Sandinistas and see some other ``democratic'' government installed there.

But it was rather surprising to hear the President say what he did, right out loud like that to the Mexican newspaper.

Meanwhile, back at the White House (from which Mr. Reagan is absent, vacationing at his California ranch), a spokesman staunchly insists that no, the President's remarks represent no change in administration policy.

The camel works its way into the tent bit by bit, counting on the occupant's getting used to its presence at each stage.

The President has been grinding down congressional resistance to limited contra aid (the $100 million package that has been debated and voted up and down on Capitol Hill all year). Meanwhile, the implicit Reagan goal of increased US involvement in Nicaragua, including US troops, to oust the Sandinistas has lain there on the table, unspoken and undebated, while the sideshow over ``limited aid'' continues.

Should the US launch an invasion of Nicaragua -- and it wouldn't be the first time -- the American public could hardly claim it wasn't warned. But somehow its resistance, like the tent dweller's to the camel, has been numbed.

The Sandinistas have been guilty of abuses; criticism of Reagan policy should not be misconstrued to imply excusing or overlooking these evils. But the best way for the US to encourage democratic reforms in Managua is to set a democratic example -- which presumably precludes barging into Managua's quarters unbidden.