The brand-new U.S. embassy in Moscow, built at a cost of $190 million, is more than just a monumental waste of the American taxpayers' money.

Worse yet, stands as a monument to American gullibility and laxity.Two years ago, it was discovered that the new embassy is riddled with electronic bugs enabling the Soviets to listen in on whatever goes on there. So extensive, in fact, is the bugging that Chairman Dan Mica of the House Foreign Affairs subcommittee on international operations says the building "would make some of James Bond's ploys look like child's play."

That's what comes of letting the American embassy be built by Russian workers using Russian materials, many of them prefabricated and hence easy to load with listening devices.

Under the circumstances, it's easy to understand why President Reagan reluctantly decided this week to raze and rebuild the embassy - with Americans labor and materials, of course - even though the replacement will cost more than $300 million and take five years to complete. Despite the steep cost, the price of keeping the microphone-infested embassy would be even greater in terms of impaired national security.

What's not so easy to understand, however, is Washington's decision to bill the Soviets only $29 million in reparations not for the bugging but just for shoddy workmanship and construction delays. Instead, with Moscow insisting that America's complaints about the new embassy are overblown, let's put those Soviet claims to the test. If the Soviets really believe the building is acceptable, let's demand that the Kremlin buy the structsure and pay full price.

Meanwhile, this fiasco should have taught America a costly but valuable lesson about how much Russia has really changed its ways and about how much the Kremlin can be trusted.