LATE this month, according to an announcement made by President Clinton on April 30, a total trade embargo on Iran is scheduled to go into effect. When stiff restrictions are being placed on US activities in another country, it is appropriate to ask what threat Iran poses to the United States.
Clearly, relations between Washington and Tehran have been seriously troubled since the fall of the shah in 1979. The Iranians have made the US -- ''the great Satan'' -- the primary object of their enmity. Such rhetoric, however, is a questionable rationale for a draconian response from the US. The immediate reasons are more substantial; they include Iran's reported efforts to develop nuclear weapons and its support for international terrorism.
Concern over nuclear weapon development in Iran is consistent with the US emphasis on preventing nuclear proliferation. But other stated reasons for embargoing Iran raise questions.
A case can be made that Iranian possession of a nuclear bomb could pose a serious threat to the world's oil supply. Iran's immediate neighbors in the Gulf, however, who might seem the most threatened, maintain normal -- if wary -- relations with Tehran. European powers, which receive more oil from the Gulf than does the US, have shown no willingness to follow Washington's lead and, furthermore, will probably benefit from trade and oil exploration opportunities abandoned by the US action. Japan, another prime user of Gulf oil, is similarly unenthusiastic.
Iran's firm opposition to the Middle East peace process is still another reason, yet Iran is by no means the only Muslim country opposed to peace with Israel. Neither is it the only Middle Eastern country suspected of supporting terrorists.
The US action can only be fully understood in the light of a fundamental objective of Washington's policy in the Middle East: the security of Israel. It is Israel that feels most threatened by Iran through Iran's support for the Hizbullah movement, source of most of the attacks on northern Israel and Israel's enclave in southern Lebanon. Much of Iranian rhetoric is directed not only at the peace process, but at the existence of the Jewish state. An Iranian nuclear weapon with an adequate delivery system would pose a serious threat to Israel.
In fact, if one looks closely at US nonproliferation policy, the stiffest sanctions imposed on putative nuclear states are against Muslim countries. The Pressler amendment, which prohibits US assistance and military sales to Pakistan, is justified by some of its supporters on the grounds of preventing ''an Islamic bomb.'' It is not necessary to add that such a bomb would pose a threat primarily to Israel.
The actions taken toward Iran and Pakistan are in contrast to policies toward other countries with potential nuclear weapon programs. US relations with India have never been warmer. And, despite the threats from North Korea, the US is not only making political concessions but is also prepared to facilitate the supply of light-water reactors for a nonmilitary nuclear program. No such efforts at genuine negotiations are being made with either Iran or Pakistan.
Although US support for Israel's security is understandable in terms of the strong domestic support for the Jewish state, it can be asked whether the sacrifices the US is making on behalf of nonproliferation in countries that conceivably could pose a threat to Israel are really necessary. Few doubt that Israel, with the strongest nuclear arsenal in the Middle East, has an unchallenged deterrence capacity. Clearly, however, neither Israel nor the US wish to depend upon the prospect of mutually assured destruction as the cornerstone of peace in the Middle East.
Occasionally over the last half-century, the possibility of a formal security treaty between the US and Israel has been raised. The idea has been rejected because of its possible impact on relations with the Arab world. The embargo on Iran once more makes clear that, given the strength of support for Israel in the US, a formal treaty would be superfluous.