From China through Russia to Poland, events announce a crisis in communism. The Marxist system of centrally directed economics has proved unequal to the demands of rapid technological development.

But reform comes hard to communist leaders -- for both political and economic reasons. The more so as the United States shows no capacity to influence communist behavior.

China affords the best example of the huge difficulties communist countries experience in generating economic reform. That country's present leader, Deng Xiaoping, has made reform the centerpiece of his program. He has had everything going for him -- experience, determination and widespread popular dissatsfaction with the last days of Mao Tse-tung and his heirs in the Gang of Four.

But four years after taking power, Deng is only now effecting the sweeping government shake-up necessary to ram home. At the current meeting of the People's Congress in Peking, the prime minister, Hua Guofeng, will lose his office and five deputy premiers will also be dropped. That hacking away shows how much the communist bureaucracy has to change in order to free up the economy.

Another source of resistance to modernization identifies itself in the person of the defense minister. Though 78 and senile, Marshalk Xu Xiangqian is hanging in there. Deng could obviously not get agreement from the military on a younger replacement. The soldiers seem to resist change because it moves toward an emphasis on consumer goods and away from the heavy industry that favors them.

The party and the army can dig in so effectively because more than self-interest is involved. Economic reform, by favoring the educated in the cities, works against equality. It also frees up prices, and thus promotes inflation.

Moreover, there is no certainty the changes will yield economic benefits. Poland supplies abundant evidence that reform does not succeed quickly. The communist leadership there, under pressure of internal unrest, has advanced the country quite a ways down the path of econmic liberalization. Agriculture is almost entirely private. Western capital is being used to promote modern industry with commodity exports paying the bill.

But the recession in the West has reduced Polish export income. Poland's import bill has soared because of the worldwide increase in oil prices last year. The government, trying to make ends meet, moved to raise the price of subsidized meat. The response of the workers was a wave of strikes. Even if the settlement holds, it is not clear how Poland can pay its bills without a touch of the austerity that invites more unrest.

As to the Soviet Union. President Leonid Brezhnev has repeatedly appealed for "measures for perfecting the whole econmic apparatus." Those appeals have been successfully resisted by the party bureaucracy and the military, and it is easy to see the reason. Why change the mix when the emphasis on military expansion and heavy industry was yielding advantages over the United States all around the world? Especially since the United States, while not wielding sticks against bad behavior, was also not offering any rewards for good behavior.

That calculus could be changed by the Polish troubles. The strike embarrassed Moscow throughout the communist bloc, in many parts of the Third World and in Western Europe. The right kind of American approach on arms control could probably open the way for major concessions from Moscow.

But what American leader can move in that direction now? Reagan by talking of arms control, could show himself to be in the Nixon tradition of hard-liners who know how to deal with Russia from a position of strength. But having been burned on China, he seems afraid even to mention foreign policy.

The Carter administration has occasion for a move on arms control when Foreign Minister Andrei Gromyko comes to the United Nations later in the month. But Secretary of State Edmund Muskie, four months after taking office, has not yet made himself master of foreign policy in any aspect. Unless the secretary asserts himself now, the president will stay hooked to the line of belated confrontation from positions of weakness -- to late and too little. That, in effect, means giving the Russians nothing to lose when they behave recklessly and, when they behave responsibly, nothing to gain.