They’re even being tough retroactively. Having signed the CFE treaty, the Soviets are now exploiting a loophole created by the United States: the exemption of naval forces from limits on military equipment and weapons systems. With Gorbachev’s apparent acquiescence, the military has redefined three motorized infantry divisions, along with their 2,600 weapons, including 800 or so tanks, as “coastal-defense units.” The Soviets also reassigned some 1,000 arms and about 1,700 armored personnel carriers to legitimately exempt units. CFE signatories, including other members of the Warsaw Pact (whose military wing is due to be dissolved March 31), saw the omissions as clear violations.

That began a political chain reaction. On his recent trip to Moscow, U.S. Secretary of State James Baker told Gorbachev that unless Moscow makes good on the CFE treaty, Washington won’t press for completion of START. And without a START accord, Baker warned, there can be no Bush-Gorbachev summit, which both sides had hoped to hold by the end of June. START, which aims to reduce Soviet and U.S. nuclear arsenals by about 30 percent, was all but wrapped up as long ago as last May. A few technical obstacles remained, such as counting rules after a “downloading,” or reduction of the number of warheads on existing ballistic missiles. But these seemed surmountable.

The impasse may yet end. In mid-March, say U.S. officials, Gorbachev offered Baker a compromise on CFE, a proposal to include within the treaty’s coverage roughly half the disputed tanks and weapons. U.S. negotiators countered by suggesting the Soviets include all disputed arms. Ultimately, the resolution will probably depend on Gorbachev’s grip on power. Last month, according to Soviet sources, he was prepared for the sake of good relations to let the United States have its way on CFE, but backed down after his military chiefs objected. Gorbachev has already won one round against the military - ratifying a treaty that allowed a unified Germany to join NATO. He must win another if arms control is to have a second round of its own.