IT is a puzzlement. The Reagan administration rings alarm bells over the possibility of a Soviet strategic base in Nicaragua. Yet, given the opportunity to pursue agreements that could effectively rule out that possibility, it crosses its arms and does nothing. Several times during the past several weeks, both the President and the Pentagon have warned of an imminent Soviet military buildup in Nicaragua. Such warnings are not new. The administration has been making them since 1981. Yet little evidence exists that the Soviets are willing to accept the costs and risks that would attend the establishment of a ``strategic base'' in Nicaragua. On the contrary, they have refused financial assistance to the Sandinistas and cut back on oil supplies. Soviet niggardliness was doubtless a principal factor prompting the Sandinistas to get down to serious efforts to end the war.
But even if the administration has exaggerated the Soviet threat, the United States does have legitimate concerns regarding Moscow's intentions in Nicaragua. The Soviets may not have any plans just now to operate their nuclear-missile submarines out of Nicaraguan west coast ports, but they might be tempted to think of doing so in the future. No Soviet bombers are now based at the Punta Huete airstrip, but what assurance does the US have that there will be none in three or four years?
Hence, thoughtful critics ought to focus not so much on the administration's tendency to exaggerate the problem as on its way of dealing with it - or, more accurately, of failing to deal with it. The administration has thought of nothing better to do over the years than to organize and aid the contras; it is a sterile approach that never even addressed the issue of Soviet arms in Nicaragua. How, after all, were the contras supposed to keep Soviet submarines out of Nicaraguan ports, unless they could defeat the Sandinistas outright? Even senior US military people have long acknowledged that they did not have that capability.
In any event, Mr. Reagan's contra policy has now collapsed around his ears. Twist and turn though he may, he has no one to blame but himself. The end came on March 3 when he urged Republicans to vote against the Democratic leadership's contra-aid package; it contained no military aid but would at least have fed and clothed the contras for several months. Stunned by the administration's rejection of the package, contra leaders concluded that it was time to reach the best deal possible with the Sandinistas rather than to remain hostage to the vagaries of the administration. Thus, they agreed to begin serious negotiations with Managua.
President Reagan's dispatch of troops to Honduras was a desperate and transparent effort to revive a failed policy to which he had already given the coup de gr^ace. The ploy failed. The Sandinistas and contras signed a cease-fire agreement anyway and will soon discuss other issues. Congress is willing to provide the contras with food, medicines, and clothing for the next several months. Military assistance, however, is probably out. The whole contra option is for all practical purposes finished.
Yet the President seems incapable of turning to more hopeful options. He refuses, for example, to pick up negotiating proposals. The Sandinistas have repeatedly offered to negotiate agreements with the US that would address all its security concerns. And during the US-Soviet summit in Washington last December, Mikhail Gorbachev proposed mutual superpower restraint in Central America.
The precise formula has been obscured by contradictory statements from the White House and the Kremlin. But from subsequent Soviet clarifications, Moscow proposes that the US and Soviet Union support the Central American peace plan by agreeing to limit their respective arms shipments to Central American nations. The Soviets even vowed to limit their shipments to Nicaragua to ``police equipment.'' Soviet Foreign Minister Eduard Shevarnadze repeated the proposal in Washington last week.
The administration's response? To label the Soviet proposal ``ludicrous.'' As one administration official put it: ``Neither reciprocity nor mutuality have any place here. This is our backyard. The Soviets must halt their military assistance to Nicaragua, but we aren't going to halt our own to the other Central American countries.''
Well, at least he was candid. And, to be fair, the US does have certain bottom-line commitments to the Salvadorean and Honduran military on which it cannot - and ought not - renege. But that simply means that negotiations would be needed to establish what kinds and levels of curbs would be acceptable to both sides. It does not mean the US should refuse to negotiate. And surely the Soviets cannot be expected to end or reduce their defense assistance to Nicaragua without some matching commitment from the United States with respect to the neighboring countries.
The US demands symmetrical cuts in Afghanistan. How, then, can the US seriously insist on asymmetry in Central America - with the bulk of the cuts on the Soviet side? But that is what the administration is demanding. Since the Soviets insist on mutual limits, the US so far refuses to negotiate. As a Soviet diplomat put it in Washington recently: ``We have made a serious proposal, one that might point toward a demilitarized region. The ball is in your court. So far, the US hasn't picked it up.''
That is unfortunate. If there is any chance of achieving through negotiations what couldn't have been won by the contras, the US ought not to let the opportunity slip. Certainly it makes no sense to sound the alarm over a possible Soviet buildup, but then refuse to enter into discussions that might prevent it.
The US does need to formalize the prohibition against Soviet military bases and sophisticated weaponry. To pin the Soviets and the Nicaraguans to a verifiable diplomatic agreement, negotiations are in order. At this point, the administration has little choice. Either it gets down to serious negotiations, or it leaves US security interests unattended, a grave dereliction of duty.
Wayne S. Smith, adjunct professor of Latin American studies at Johns Hopkins University, was chief of the US interest section in Havana, 1979-82. He is the author of ``The Closest of Enemies,'' W.W. Norton, an account of US-Cuban relations.