Ukraine Wants Own Finger on Nuclear Button : Weapons: Worried by Russia’s political turmoil, Kiev balks at ratifying key arms treaties.

Alarmed by the power struggle in Russia, Ukraine is balking at ratification of a treaty that would require it to give up control of the nuclear weapons on its territory.

Leading lawmakers said Ukraine’s commitment to ratify the U.S.-Soviet Strategic Arms Reduction Treaty is not in question. That treaty, known as START I, would lead to negotiations with Russia on eliminating the 176 intercontinental ballistic missiles that Ukraine inherited from the Soviet Union.

But the lawmakers are worried that if Russian President Boris N. Yeltsin falls from power, a new government in Moscow that is unfriendly to the West would gain the key to firing those missiles westward while they are still in place.

“We don’t know who is going to end up with the launch button in Russia,” said Serhij Semenets, a member of Parliament’s disarmament commission who is not alone in believing that Ukraine’s northern neighbor will remain politically unstable for some time to come.

“Today, missiles could be launched from Ukraine without our approval,” he said in an interview. “And the United States would then retaliate against the source of the attack--Ukraine.”

According to Semenets, influential lawmakers have decided that Ukraine must avoid such a scenario by rigging the weapons to make it impossible for Russia to launch them without Kiev’s approval. The options range from dumping sand atop the missile silos to installing electronic barriers on the communications systems that transmit launch orders from Moscow.

Such preventive steps would not be prohibited under START I. But legal experts here argue that any intrusion by Ukraine in the launch sequence now controlled by Russia might violate another pact, the Nuclear Non-Proliferation Treaty. Any nation ratifying that 1968 treaty pledges not to acquire, develop or take control of nuclear weapons.

“If Ukraine becomes non-nuclear it has no right to own or control the nuclear weapons on its territory in any manner, including blocking control,” Semenets said. “If they cannot be Ukrainian weapons, then they become Russian weapons.”

Ukraine has signed both treaties and is under strong pressure from Washington to ratify them. But Semenets said that “a noticeable number of deputies who were undecided” about the non-proliferation treaty have swung against it since conservative forces in Russia began trying to oust Yeltsin.

Yuri Kostenko, head of the parliamentary commission, said in a separate interview that the vaguely worded non-proliferation treaty is unsuited for Ukraine, which gained a nuclear arsenal by inheritance rather than design. The treaty, he said, does not spell out how Ukraine is to give up the weapons.

Nor does it address the complex and uncertain division of control over the weapons between Russia and Ukraine.

“No one fully controls the weapons in Ukraine today,” Kostenko said. “Russia has the launch button, but it cannot remove the weapons from our territory without military force.”

After the Soviet Union collapsed in 1991, strategic rocket forces manning its arsenals came under the Moscow-based joint command of the Commonwealth of Independent States, whose military chief is Russian.

Then last spring Ukrainian President Leonid Kravchuk subordinated those forces in his country to the new Ukrainian Defense Ministry. Kiev has been paying their wages and supplying their housing and logistic support ever since. All soldiers in those units took loyalty oaths to Ukraine, but not all the officers did so.

Through special communications lines that connect Moscow to computer systems inside the weapons, the missiles can be launched by the push of a button in Russia.

A breaker was recently installed to allow Kravchuk to veto launches. Instead of transmitting orders directly to the missile silos, Moscow routes them to the Commonwealth’s 43rd Rocket Army headquarters in Vinnitsa, a Ukrainian city near the missile fields in Derazhnia and Pervomaysk and about 120 miles southwest of Kiev.

According to procedures negotiated between Ukraine and Russia, the commander in Vinnitsa would, upon receiving a launch order, call Kravchuk on a special phone line for his approval before passing on the order to the launch systems.

But Kravchuk’s input is only advisory. Nothing physically prevents the commander, who has not pledged loyalty to Ukraine, from ignoring Kravchuk and proceeding with the nuclear attack.

Semenets said that political turmoil in Russia should persuade the West to support Ukraine’s efforts to take greater control over the nuclear arsenal on its territory.

“Ukraine is politically more stable than Russia,” he said. “If we had the technical capacity to block launches, that would mean that at least a portion of the ex-Soviet arsenal would pose less of a danger.”

But even if that support is not forthcoming, Western disapproval is unlikely to deter the lawmakers, who are not only fearful of Russia’s threat to Ukrainian independence but also disillusioned by Washington’s reluctance to give Ukraine formal security guarantees.

Some lawmakers say Ukraine should ratify the treaty as a “nuclear weapons state”--a temporary status lasting only until all the weapons on its territory are destroyed under the START I pact.

Others have suggested that Ukraine delay ratification until 1995, when the non-proliferation treaty comes up for renewal.

By then, those lawmakers say, the future of Ukrainian-Russian relations may be clearer, as may the fate of nuclear weapons in Ukraine.