As Turkish Prime Minister Bulent Ecevit visits President Clinton today, an important and highly sensitive subject belongs on the agenda.

As a staunch ally of the United States, Turkey is unique. It is the only member of NATO that has sought entry into the European Union (EU) without success. The three most recent NATO members -- Poland, Hungary and the Czech Republic -- are already engaged in accession negotiations with the EU, but Turkey, whose NATO membership dates back to 1952, has been kept at arm's length. Is there anything the United States can do to counter the deep disappointment and alienation felt in Turkey at being excluded from full acceptance into an ever more economically integrated European community?

During the Cold War, Turkey was regarded by the United States and its Western allies as the main bulwark against the southern expansion of Soviet power. Among NATO countries, its military establishment has ranked second in size to that of the United States. Since the end of the Cold War, Turkey has continued its close security cooperation with the United States. It played a key role in the U.S.-led Gulf War, its soldiers joined U.S. troops in international peacekeeping operations in Bosnia, and it provided valuable logistical support to the recent U.S. air operation in Serbia. As the only firmly established secular democracy among Muslim states, Turkey is vital to U.S. interests in sensitive regions, including the Balkans, the Caucasus, the Middle East and Central Asia.

In order to consolidate its secular and pro-Western orientation as well as tighten its economic links to Europe, Turkey has sought full membership in the EU virtually from the organization's inception. The EU, however, has decided that Turkey does not yet meet the required criteria. Instead, the EU signed a customs union agreement with Turkey, which went into effect on Jan. 1, 1996. While Turkish officials initially considered the customs union a step toward full membership, it soon became clear that the European Union regarded it as a substitute for full membership.

Despite continuing official EU reaffirmations of Turkey's eligibility for full membership, the reality of de facto rejection has increasingly sunk in. Not only is Turkey omitted from the list of countries (Poland, Hungary, the Czech Republic, Slovenia, Estonia and Cyprus) with which accession negotiations have already begun, it is also left out of a projected second wave of expansion that will include five additional countries: Bulgaria, Romania, Lithuania, Latvia and Slovakia.

Why is Turkey being excluded? A variety of reasons have been given, including the Kurdish problem and related issues of human rights, Turkey's macroeconomic situation, and the opposition of Greece because of the Cyprus situation. But there is some indication of a softening of the Greek position, provided Turkey does not place roadblocks in the way of Cyprus's current efforts to join the EU. As for the Kurdish problem, Turkey is making progress in working out a peaceful solution. And the EU acknowledges that the country is headed in the right direction in reforming its economy.

If EU standards for resolving these problems are ultimately met, will Turkey then be admitted? Many Turkish leaders believe this unlikely because of officially unspoken EU apprehensions. Turkey's population of 64 million is second in size only to Germany's among present and prospective members of the EU. In some European circles, this sends up several red flags. If admitted, would Turkey exert undue weight in EU decision-making? With EU membership entailing the free movement of workers, what effects would the admission of a populous and relatively low-income country have on European labor markets? And finally, would the EU be willing to integrate fully with a country that is almost entirely Muslim? None of these considerations is discussed openly, but they are clearly in the background of the debate.

The EU's equivocation has bred Turkish disaffection from Europe and plays into the political hands of the Islamists who as recently as 1996 were at the helm of the government. Clearly, the enormous U.S. stake in a secular, Western-oriented Turkey warrants action by the United States to offset the EU's arm's length treatment and to strengthen and solidify the country's Western political and economic integration.

One such step would be for the United States to offer to negotiate a free-trade agreement with Turkey. Indeed, there is precedent for such a bilateral agreement, one motivated more by political considerations than economic advantages, and that is the 1985 U.S. free-trade agreement with Israel.

But the economic rationale for such an agreement with Turkey should not be dismissed. For Turkey the advantages are obvious; the United States ranks second as a market for its exports and third as a source of its imports. For the United States, Turkey is one of the world's 10 big "emerging markets," and this country is Turkey's largest foreign investor.

A U.S.-Turkey free-trade agreement would not be a substitute for Turkish membership in the EU, a goal that Turkey should continue to pursue as it gets its political and economic house in order. But it would help compensate for a growing belief in Turkey that the country has little prospect of entry into the EU mainly because of European prejudice against a Muslim country. In light of Turkey's strategic role as a U.S. ally in a rough neighborhood, a U.S.-Turkey free-trade agreement would help consolidate Turkey's Western orientation and contribute to stability in a highly volatile region of the world.

The writer is William L. Clayton professor of international economics at Johns Hopkins University's School of Advanced International Studies.