PERVOMAYSK, Ukraine (AP) _ Defense Secretary William Perry stared over the brink of a Ukrainian missile silo Tuesday and saw a sign of peace.

In an unprecedented tour of a former Soviet intercontinental ballistic missile base, Perry witnessed the gradual dismantling of a site that had possessed the power to inflict heavy damage on the United States.

The trip marked the first time any U.S. defense secretary has visited an ICBM base or missile facility in the former Soviet Union.

The gaping SS-24 missile silo into which he peered contained a rocket some 9 feet in diameter, but none of the 10 nuclear warheads that it can carry. They have already been removed and shipped to Russia for dismantling.

Perry also toured the underground command center that controlled some of the 700 warheads at Pervomaysk. Ukrainian officers demonstrated the steps they would have taken to prepare for launching missiles.

''As I stood there watching this process, I admit that I was awed,'' Perry said afterward. ''These two operators had the power to destroy every major city in the United States.''

Already, the danger is decreasing, Perry said.

Ukraine has shipped 120 warheads to Russia, where they will be disarmed. Half of those came from SS-24s at Pervomaysk.

Perry profusely thanked his hosts for ''this historic trip,'' noting that no defense secretary had ever visited the base in south-central Ukraine.

''Two years ago, a secretary of defense could not even have imagined going to these sites,'' Perry said.

The tour was fitting in one sense. The United States is providing some of the money the Ukrainians need to dismantle their nuclear arsenal. Perry listened impassively as the Ukrainian officials explained their critical shortage of funds.

Deputy Foreign Minister Boris Tarasiuk, the top Ukrainian arms control negotiator, said the $350 million already provided or promised by the United States for this purpose, some of it signed over on Monday, amounts to only a fraction of the total cost.

Tarasiuk estimated it will require $2.8 billion to remove warheads, dismantle rockets and destroy silos.

As Perry descended a narrow stairway into the command center, Ukrainian Defense Minister Vitaly Radetsky cracked, ''Keep the minister until he gives money.''

When they looked down into the SS-24 silo, Radetsky assured Perry that 30 of the base's 46 SS-24s have been deactivated, and he invited Perry to look into any silo he wanted.

''We'll have a bet on this one,'' Radetsky said. ''If there is a warhead, we'll pay. Otherwise, you pay.''

That, of course, is precisely what the United States is doing.

Perry defended the cost to U.S. taxpayers, noting the obvious, direct benefit of helping Ukraine.

''This seems like a lot of money but it buys us more defense than any other use of defense dollars that I could think of,'' Perry said.

Col. Gen. Volodimir Mikhtiuk, commander of nuclear forces in Ukraine, told of soldiers working round the clock to meet deadlines set by previous arms- reduction agreements. Some, he said, are homeless, and the base lacks money to buy spare parts for equipment involved in the dismantling process.

Without outside help, Mikhtiuk said, ''We would be forced to stop.''

In addition to the SS-24s, Ukraine also has 130 SS-19 missiles, each of which can carry six warheads. Half of the 40 SS-19s at Pervomaysk have been deactivated. And of the 90 SS-19s at Ukraine's Khmelnitsky base, Radetsky would only say that ''a lot'' have been deactivated.

The Ukrainian farmland surrounding Pervomaysk would be familiar to anyone from the upper Midwest, where many of America's ICBMs are based. Fields stretched out in all directions and as the military leaders looked at the tools of Armageddon, farmers plowed for their spring planting.

Earlier in the day, Perry placed a wreath at a memorial in Kiev to World War II dead. A military band played the Ukrainian and American national anthems while soldiers, their uniforms matched by the steel-gray sky, kick- stepped past.