WASHINGTON (AP)—The Reagan administration’s top nuclear arms negotiator says it would be “highly unfortunate” if the Senate amends the U.S.-Soviet treaty eliminating atomic-tipped missiles from Europe.

“I don’t think a condition is in the best interests of the United States,” Max Kampelman told the Senate Foreign Relations Committee.

Kampelman was responding Tuesday to a proposal by Sen. Larry Pressler, R-S.D., a conservative critic of the treaty signed last month. But he also had a similar response to a pair of liberal senators who suggested reservations.

Kampelman’s comments were part of an effort by the Reagan administration to win Senate approval of a so-called “clean” treaty, one without any reservations or amendments that would require reopening negotiations with the Soviet Union.

Those proposals have been dubbed “killer amendments” because they could mean that the Intermediate-range Nuclear Forces treaty would not take effect unless the conditions were met. The treaty requires both nations to eliminate all missiles with ranges from 315 to 3,125 miles.

Kampelman said, “I do not believe it would be wise or that it would move us forward” to attach conditions.

Pressler asked Kampelan for his reaction to an amendment requiring numerical parity between NATO and Warsaw Pact troops. That would mean a reduction in Soviet troops, since the Warsaw Pact has more forces than NATO.

“That would be highly unfortunate,” Kampelman answered. “It would mean the INF treaty would not be put into practice for a long period of time” because the two sides have negotiated unsuccessfully for 15 years to cut the number of troops.

Kampelman gave a similar answer later to Sen. Nancy Kassebaum, R-Kan., who asked his ideas about an amendment requiring U.S. withdrawal from the pact if the Soviets are found to be in violation.

Maynard Glitman, who headed the INF negotiating team, said the pact contains a clause permitting either side to drop out because of “supreme national interest.”

Earlier, Sen. Joseph Biden, D-Del., suggested an amendment requiring an “interim” agreement freezing both superpowers’ arsenals of long-range atomic weapons. Those arsenals are the subjects of the ongoing U.S.-Soviet talks known as START, for Strategic Arms Reduction Talks.

“You are trying to find a formula to supplement the INF treaty,” Kampelman told Biden. “We have a good shot at getting a START treaty in the next months or so and we would much rather concentrate our energies on that complicated procedure.”

When Sen. John F. Kerry, D-Mass., later raised a similar link, Kampelman said, “We’d be better off spending our time on START.”

Kampelman also sparred verbally with Sen. Jesse Helms, R-N.C., who has thus far been the committee’s most vocal critic of the INF treaty.

Helms renewed his complaint that administration officials are falsely describing the treaty as requiring the destruction of nuclear weapons when actually, the pact only requires the destruction of missiles. The warheads can be used for other weapons.

“I don’t see how this treaty reduces nuclear stockpiles in any degree whatsoever,” Helms told Kampelman, referring to the fact that the fissionable material in the warheads could be recycled.

Kampelman answered that “I don’t think you can look at it in terms of how much fissionable material is lost or saved.”

“Fissionable material is what goes boom,” said Helms.

Kampelman answered that “they don’t go boom by themselves … they need the things we’re destroying.”

“It’s very hard to pick up this nuclear warhead and throw it at someone. That’s why you have to have the missile,” said Kampelman.