Professional Kremlin-watchers, in both government and academia, are enjoying a feast of new information under "glasnost." Some recent revelations raise fundamental questions about the assumptions made by U.S. strategists.

For example, revised estimates about the Soviet economy now peg it at only about one-third the size of ours much lower than previously thought. If these estimates are correct, military spending is probably absorbing about 35 percent of Moscow's gross national product nearly twice the proportion that had been calculated by the CIA. The corresponding figure for U.S. defense spending is only 6 percent.The costs of empire seem to be even more burdensome to the Soviets' frail economy than Washington has assumed, and the pressures on Mikhail Gorbachev to trim that burden even greater. U.S. arms control negotiators should take note.