Exploding mines in the Red Sea made front-page world news this week, but far more important to all foreign offices was a surging bull market in Wall Street. It advertised the fundamental strength of the American economy at a time when Moscow's relative economic weakness is much in evidence. (It would also seem to point toward a likely reelection for Ronald Reagan which, in the minds of NATO allies, is welcome as meaning the prospect of stability in American foreign policy.)
Moscow's relative economic weakness is exposed by two major developments within the Warsaw Pact community which Moscow complains about but cannot prevent. The Soviet press this past week criticized the East German government for being tempted by West German gold, and the Polish government was being tempted by the prospects of renewed American trade.
In both cases Moscow's satellites are reaching westward for the economic help Moscow is incapable of providing.
The most interesting facet of these matters is that the East German government, normally the most subservient of all the satellites to Moscow's every wish and whim, is talking back. Plans went ahead for East German leader Erich Honecker to visit West Germany in late September.
Also the East German controlled press printed Moscow's latest criticism, but also an earlier Pravda editorial which had favored detente.
And it reprinted an editorial from a Hungarian weekly which said the small countries of East and West should ''increase their efforts to preserve detente.''
Moscow was particularly critical of relations between East and West Germany over the announcement in Bonn on Aug. 2 of a bank credit to East Berlin of $330 million. Moscow spoke of ''increased revanchist solicitations.'' It also made known its dislike of a second agreement between the two Germanys to ease travel regulations.
The essential fact in world affairs is that West Germany, an ally of the United States, is financially able to offer bank credits and other forms of economic aid to East Germany which East Germany needs and does not get from Moscow.
With Poland the story is the same. The Polish economy is dangerously weak. Without improvement there are likely to be more public demonstrations against the government and in favor of the banned trade union organization Solidarity. Loans, trade, and technology from the West are essential to Polish economic revival. They can be had only by lenience toward the Polish people and amnesty for most of the imprisoned Solidarity activists.
Moscow must watch while the Communist government of Poland does what must be done to obtain more credits and trade with the West.
It galls. It must be particularly disappointing to the Kremlin that the surge in Wall Street last week, the biggest ever in volume of shares traded and extent of rise in values, seemed to forecast a decline, rather than a rise, in American interest rates.
The market was up not because more inflation is expected, but because the inflationary pressures in the economy have subsided in spite of the current budget deficit.
The American economy is in fact cooling. Leading economic indicators declined just enough in June to indicate a slowing down.
At the same time unemployment moved up, slightly, from 7.1 to 7.5 percent.
Both the slowing in growth and the rise in unemployment indicated a decline in inflationary pressure. Add that the productivity rate is rising, while wages remain stable with only slight rises in some areas.
In any foreign office the meaning is evident, and clear.
The foundation of the NATO alliance is the American economy. There have been worries about the soundness of that foundation. The rising American deficit meant rising US interest rates. This drained the allies of investment capital and seemed to point toward a revival of dangerous inflation in the US.
But now those anxieties seem to be washed away by that surge of buying in Wall Street. Fears of renewed inflation have been lessened and a decline in American interest rates is expected. That would release foreign funds from the American market for use at home.
In other words, the implication is that the American economy is so healthy and sound that it can stand up successfully under both the arms and the debt load which Mr. Reagan has put on its back. The load is heavy, but apparently the horse can take it and keep going.
Not everyone in all the allied countries necessarily applauds the political implication that Ronald Reagan is running for reelection on the most attractive of all possible bandwagons - economic prosperity. If Wall Street is correct in assuming declining interest rates, it follows that Mr. Reagan's prospects are high, and improving - even though he was in temporary difficulty this past week over tax policy.
In European eyes, Mr. Reagan is conservative and too much of a ''cold warrior'' for comfort.
But he is also predictable. Everyone knows where he will stand on any issue - including birth control. There is no need to puzzle over where he will be tomorrow or the next day. NATO foreign offices remember with dismay the vacillations of Carter foreign policy.
The predictability of Reagan foreign policy is a plus.
Meanwhile, the mines exploding in the Red Sea were distressing, and a nuisance. Some Westerners suspect Iran is responsible, directly or indirectly. But it is a minor matter alongside the accumulation of indications that the American economy is steady and sturdy.