MOSCOW -- The Soviet Union does not need emergency food aid. But its big cities do. Moscow, Leningrad and the other large municipalities controlled by non-Communist political forces are caught in a vicious political squeeze play that worsens shortages created by distribution and market-pricing problems.

While the West debates whether and how to extend aid, food becomes a central element in an extended power struggle that could determine the fate of the new Russian revolution. This political struggle makes it in the long-term interest of America, Western Europe and Japan to mount a major relief effort now.

The West continues a go-slow approach, even while making more sympathetic noises about the lengthening food lines forming in big Soviet cities as winter deepens. Three main points of argument are advanced to explain this caution:

First is the accurate reporting from the U.S. Embassy and other diplomatic missions that, as a nation, the Soviet Union is not short of food. The good harvest collected this autumn should have set the stage for a better than usual winter for the Soviet consumer. After processing, the Soviet grain crop appears to total 115 million tons.

But the inefficient Soviet distribution system seems to have collapsed under the weight of reform and the confusion of perestroika. The United States and its allies should not attempt to solve such a basic infrastructure problem through temporary aid, it is argued. The Soviets can and must do that themselves, primarily through market reforms.

The third point is in many ways the reverse of the second. Practitioners of Realpolitik argue that Soviet President Mikhail Gorbachev's regime is too weak to take advantage of a major aid program. Power has already effectively passed to the country's 15 republics. The United States should not take actions that would too closely identify it with Gorbachev's fate.

There is some merit in each of these points. But they neglect the peculiar demographic and political circumstances of Gorbachev's Soviet Union in the sixth year of perestroika, as Sergei Stankevich, the deputy mayor of Moscow and a leading non-Communist reformer, is quick to point out.

The collapse of the distribution system is as much a political phenomenon as a physical one, Stankevich suggests. Under the old command system that Gorbachev's reforms have dismantled (but not replaced), Moscow simply ordered up its food requirements from the agricultural collectives in the republics.

Now to emphasize their independence from Moscow and because they are rational economic beings, the farmers of the republics do not send their output into the official distribution system, which buys and sells at below market-prices. Goods are widely available for those who have the wealth and contacts to be part of the "black market" that is gradually becoming the Soviet Union's only real market.

Stankevich says there is another reason why Moscow, Leningrad, Donetsk and other urban centers confront severe shortages. Non-Communist reformers committed to Western-style democratic freedom captured control of these municipalities in the last local elections. Orthodox Communist apparatchiks still control much of the agricultural organization and use their power to try to strangle the new authorities who want to break up Communism.

"One quarter of Moscow's 8 million people live on pensions and other fixed incomes that the national government cannot raise to match market price increases," Stankevich says. "In Leningrad, it is about one-third of the population that is in this situation. They are the ones who are hurt by these shortages and who have to stand in those long lines to find empty shelves."

The Moscow city administration, which has been critical of Gorbachev for not making a clean break with the Communist party and its policies, is also subject to pressures from the central government. The Kremlin has cut the foreign-exchange allocation the city could have used to buy medical supplies and emergency food from abroad from $270 million three years ago to $15 million this year.

In 1991, the Moscow authorities will get no foreign exchange from the central government at all, Stankevich said.

The breakdown in food supplies undermines support for radical reformer Boris Yeltsin and his Russian Federation government, which also challenges both Gorbachev and the hard-line Communists. Across the Russian heartland "there is primitive bartering of food for anything except for money," says Gennady Filshin, deputy prime minister of the Republic of Russia.

Filshin avoided answering directly when I asked him if President Bush's offer of agricultural credits, as opposed to free food supplies, would be helpful. But his answer suggested that the West is doing too little too late to help non-Communist reformers keep the places in power they have won:

"The people are just not prepared to wait for a long time for relief from their desperation. If this government is overturned by empty shelves, then you can be sure the next government that will come to power will be totalitarian and conservative."