The decision by Mikhail Gorbachev this week to begin a military crackdown against seven breakaway republics bodes ill for the future of the Soviet Union. All the experiments with freedom and glasnost and a free market economy could fall victim to the strongarm efforts to hold the nation together.

Of the 15 Soviet republics or states, half want out, and Gorbachev and his associates are worried that if they allow independence to any of them, the floodgates will open.They are probably right. The very survival of the Soviet Union as we know it is at stake, and Gorbachev's right to govern is increasingly threatened. No wonder he dispatched troops to the republics to enforce the Red Army draft in an effort to protect national security.

While that action can be condemned, the risks of doing nothing may be even greater, as far as the suvivability of the Soviet Union is concerned.

Thousands of young men in the republics are ignoring Red Army draft orders, and many are performing alternate service such as hospital or social work under laws passed by the republics but considered invalid by the Kremlin.

Critics in the republics fear that the act of sending troops might be a pretext to start bloody suppression - a use of force on a massive scale. Others fear the restoration of dictatorship - the very reason Foreign Minister Eduard Shevardnadze resigned.

The fact that the Baltic republics have been working out details of a disobedience campaign against the Soviet military makes the possibility of violence even more ominous.

Latvian leaders encouraged Latvians to participate in massive acts of protest in the event of a crackdown, and Lithuanian and Estonian leaders encouraged draft-age young men not to sleep in their own homes.

Meanwhile, the Soviet economy worsens, and there are major disagreements in the Soviet Congress over governmental restructuring - as well as between Gorbachev and Boris Yeltsin over the Russian Republic's share of the disputed budget.

Soviet officials have even suggested that domestic political problems may force a postponement of President Bush's visit to Moscow next month.

If any political leader can survive this enormous pressure, it is probably Gorbachev, but the threat of dissolution of the Soviet Union has never been so great.

If Gorbachev's questionable decision to order a military crackdown in the republics leads to massive violence, then revolution or civil war could be the next step.

And if the Soviet Union breaks into a variety of nation-states, will these nation-states fight each other? What happens to the vast array of nuclear weapons and other armaments in the country? Will the military seize power? If so, would a junta be friendly to the West? These and other questions hang in the balance.

It is likely to be a longer Soviet winter than usual - and the rest of the world will be watching and waiting to see if the Soviet Union can survive.