I agree that a planned Soviet invasion in the '80s is unlikely, but the 1973 Yom Kippur War, now that was a scary thing. Not only were the Soviets airlifting troops and supplies into Damascus, but the United States responded by beginning its own airlift into Israel while the fighting was still ongoing. Thus, you had the U.S. and the U.S.S.R. reinforcing opposite sides of a conflict with their own troops and materiel.
Worse still, the Yom Kippur War was the closest thing to a pan-Arabic war the region saw until the Gulf War. Iraq and Saudi Arabia sent troops which saw combat in Syria, and Algeria, Sudan, Lebanon, Tunisia, and Lybia all sent smaller amounts of military aid and money. (Jordan stayed out of it largely because of that cute little maneuver the Palestinians pulled on them in Black September.)
As it happened, a cease-fire was declared, but at roughly the same time the IDF in Egypt pinned the Egyptian Third Army on the wrong side of the Suez Canal. Henry Kissinger seems to think that the Soviets believed that the negotiations which were ongoing in the U.N. and between the U.S. and the U.S.S.R. was a ruse to allow time for the Israeli turning movement.
The Soviets handed Nixon a very nasty letter saying that if the fighting didn’t stop right now the United States and the Soviet Union should intervene against Israel. If America wouldn’t go along with it, the Soviets threatened to do it unilaterally. The text of that letter is supposedly available, but hell if I can find it. It is the only open Soviet threat to invade Israel of which I know.
As a result, on October 25, 1973, America bumped up its non-strategic forces to DEFCON III. Fortunately, the fighting died down and within a week everything was jake. But for a little while there things were uncertain and very, very dangerous.
As far as finding a cache of Russian equipment lying about in virtually any Arab nation, well, we usually call it that country’s armed forces. The Soviet T-55 (and occasionally a Chinese knock-off) is still one of the world’s most popular tanks, and everyone in the Middle East has 'em–including Israel, which picked most of theirs up for free, if slightly damaged, from the battlefields of Golan and Suez in 1973.