Ukraine Backsliding on A-Arms a Setback for U.S. : Disarmament: Washington used to think Kiev could be persuaded to dismantle its warheads. No more.

Last spring, the Clinton Administration made what it thought was a routine request to Ukraine’s government: to let a State Department arms control expert visit Kiev for talks on dismantling more than 1,800 nuclear warheads Ukraine inherited from the Soviet Union.

“They wouldn’t even let him into the country,” a senior official marveled. “We had to ask three times before they would even agree to a meeting.”

A year ago, American officials thought they might succeed in persuading Ukraine, the second most populous republic of the former Soviet Union, to dismantle the nuclear weapons on its territory or ship them to Russia.

No longer. Ukraine’s leaders have repeatedly promised to get rid of the weapons that would make them the world’s third-biggest nuclear power (after Russia and the United States). But they have squirmed out of making specific commitments--and they have recently begun suggesting that they want to keep their most modern nuclear weapon, the giant SS-24 strategic missile.

As a result, senior U.S. officials say they now expect Ukraine to hang on to some nuclear missiles at least until the year 2000, and probably beyond that.

That would be a major setback for the Administration, which wants to avoid creating a major new nuclear nation in the middle of Eastern Europe.

Secretary of State Warren Christopher went to Kiev last month to try to move the Ukrainians toward keeping their promises to dismantle the weapons--with only partial success.

Ukraine’s president, Leonid Kravchuk, told Christopher he is still committed to getting rid of all the weapons on his territory. And Kravchuk approved an agreement under which Ukraine will begin receiving U.S. aid to pay for the cost of dismantling and shipping atomic warheads.

But Kravchuk later said he would accept an arrangement sought by nationalists in his Parliament, the Supreme Rada, under which Ukraine initially would agree to dismantle only its oldest, least effective missiles--and hold out for more money to destroy the rest.

“Negotiating with the Ukrainians is like the myth of Sisyphus,” one senior U.S. official said. “Every time you think you have pushed the ball to the top of the hill, they roll it back down again.”

Christopher’s two days in Kiev last month were a sobering illustration of that frustrating negotiating style. The secretary of state went to Ukraine after the Kiev government said it was ready to sign the nuclear-dismantling agreement; he carried a promise of $330 million in U.S. aid as a reward.

But after a two-hour meeting, only moments before they were to begin a news conference announcing the agreement, Ukrainian Foreign Minister Anatoly Zlenko suddenly looked at Christopher and said: “We don’t think we can sign this tonight.”

“You’ve already agreed to sign,” Christopher protested.

“We have some problems with it,” the Ukrainian shrugged.

Christopher went ahead and announced the agreement anyway. Then, over steaming bowls of borscht at an official dinner at Kravchuk’s residence, he warned the Ukrainian: “My credibility is at stake here.”

The Ukrainians backed down. After a night of negotiations among their experts, Christopher and Zlenko signed the final copy of the agreement the next morning in a hurried ceremony in the sixth-floor lobby outside Christopher’s hotel suite.

But on another key issue, Christopher made less headway. The secretary of state carried a letter from President Clinton specifically asking Kravchuk to begin dismantling the SS-24 missiles along with the older, less reliable SS-19s. “We don’t have any assurance that the SS-24s are going to be included,” a State Department official acknowledged earlier this month.

That poses a problem for the Administration. If Ukraine uses millions of dollars in U.S. aid to dismantle old weapons it doesn’t want but keeps the newer weapons, then the money will have largely been wasted.

Ukrainian officials have long said they want to get rid of the SS-19s, which are beginning to suffer from maintenance problems. Last week, Russian Foreign Minister Andrei V. Kozyrev warned the Ukrainians that keeping the weapons could lead to a tragedy “greater than Chernobyl,” the nuclear power plant in Ukraine that exploded, with a vast release of deadly radiation, in 1986.

Why are the Ukrainians so adamant?

That’s easy, U.S. officials say. “It is clear what the Ukrainians want: money and security,” said one top negotiator.

The Ukrainians are still trying to figure out whether they can use the nuclear weapons as a deterrent against Russia, which ruled their land for centuries.

U.S. military experts say the Ukrainians don’t have enough control over the weapons to fire them; the troops at the missile bases still answer to Russian commanders, with firing codes kept in Moscow.

Even if they did have control, the experts say, the long-range missiles, designed for use against the United States, could not be fired accurately at Moscow, less than 500 miles away.

In exchange for giving up the missiles, the Ukrainians have asked for a direct U.S. guarantee to defend them if they are ever attacked by Russia; the United States has refused to enter a formal defense pact of that kind.

“The problem is that they don’t know what they really want,” one U.S. official said. “It isn’t that they are convinced that they want to keep the nukes. They just aren’t sure that they want to give them up. So they bounce back and forth, and it’s driving us crazy.”

The Administration’s response has been a policy that might be called “tough love”: promises of U.S. aid to help rescue Ukraine’s collapsing economy, of help in bolstering the new country’s security in a dangerous neighborhood and even of “summit” meetings with Clinton--but only if Kiev takes concrete steps toward dismantling the weapons.