Ukraine Wins U.S. Security Pledge, Official Says : Arms: Top negotiator returns from Washington with letter from Bush. The ex-Soviet land has balked at ratifying nuclear treaty.

Ukraine’s top arms negotiator, returning home from a visit to Washington, said Saturday that President Bush gave him a written summary of security guarantees that the United States intends to provide this country after Ukraine gives up its nuclear weapons.

The letter fell short of immediate, binding guarantees that were sought by the official, Deputy Foreign Minister Boris Tarasiuk. But Tarasiuk said he is satisfied with it and is confident that it will overcome concern in Ukraine’s legislature over the possibility of aggression by neighboring Russia.

“The United States has finally seen our view and understood our fears of the potential threat from Russia,” Tarasiuk said. “I expect this will positively affect the prospects for ratification” of the country’s non-nuclear status.

Tarasiuk spoke aboard an Air Ukraine flight from Newark, N.J., after three days of talks in Washington about Ukrainian adherence to the 1991 U.S.-Soviet Strategic Arms Reduction Talks treaty, known as START I, and the Nuclear Non-Proliferation Treaty.

Ukraine inherited 176 Soviet strategic missiles when the Soviet Union broke up a year ago. The new country’s leaders at first promised to ratify both treaties by the end of 1992, pledging that Ukraine would deliver all 176 missiles to Russia for destruction.

Later, however, Ukraine added conditions to its promise: a demand for guarantees that a non-nuclear Ukraine would be protected from archrival Russia and other nuclear powers, for payment of $1.2 billion in compensation for its action and for the right to use reprocessed components of the missiles to fuel its five nuclear-powered reactors.

Ukraine’s foot-dragging drew heightened attention last Sunday after Bush and Russian President Boris N. Yeltsin signed an ambitious START II accord that would cut U.S. and Russian strategic nuclear arsenals by two-thirds over the next decade. Ukraine’s ratification of START I is essential to implement that treaty and to proceed with START II.

Against that backdrop, Tarasiuk flew to Washington on Tuesday seeking a security treaty with the United States as a precondition for START I ratification. The State Department rebuffed him, but Ukrainian officials said that a compromise was then reached, allowing him to take home a document outlining U.S. guarantees that will protect Ukraine.

Tarasiuk said the United States agreed to seek similar guarantees for Ukraine from Russia, Britain and other nuclear powers.

The Ukrainian official was also given an unusual White House session Friday with Bush, who normally meets only with higher-ranking foreign officials.

“The United States finally understands that Ukraine is a new European power militarily, economically and politically,” he said. “Before, the United States viewed its relations with Ukraine through a prism of American-Russian relations. They finally realized that our interests are different.”

Tarasiuk also said he reached an understanding in Washington on financial compensation but gave no details. The Bush Administration had earlier offered initial compensation of $175 million.

Ukraine’s legislature, the Supreme Rada, is scheduled to meet Jan. 18, and its presidium has put debate of the nuclear treaties high on the agenda. A growing lobby there, made up of nationalists and former Communists, has urged the government to keep some weapons to bargain for more aid.

Ratification will hinge not only on Tarasiuk’s explanation of U.S. guarantees but on the outcome of a meeting in Moscow on Friday between Yeltsin and Ukrainian President Leonid M. Kravchuk, who intends to press the Russians for security guarantees and nuclear fuel.

In a television interview in Moscow, Ukrainian Ambassador Vladimir P. Kryzhanovsky admitted Saturday that Ukraine was using its nuclear weapons as “a trump card.”

“We are practically the first in world history to discard nuclear arms,” he said. “We want to use this trump card so that the civilized world can say, ‘Look, this is a country we can deal with. They are for real.’

“Instead, we are viewed with some suspicion. But when two countries (the United States and Russia) agree that instead of killing each other 100 times over they will kill each other only 30 times over, this is welcomed by the world community.”