Homemade but lethal bombs explode in the Paris subway while French President Jacques Chirac pursues nuclear test explosions on the South Pacific atoll of Mururoa despite the world's disapproval. It requires a big leap, but there is a French connection between these two disparate bombing campaigns.

The connection is made by colonialism, past and present. France's colonial past gives rise to conditions that encourage Algerian terrorists to bring their country's civil war to French soil. And colonialism is the most serious issue raised by the Mururoa blasts, which are less dangerous ecologically and less destabilizing politically than France's alarmist critics charge.

All countries are colonized by their past. But few take it as far as France, where the nature and meaning of the 1789 revolution is still a matter of serious debate. The election of Chirac to replace Francois Mitterrand last May was seen as a major generational upheaval in France: A veteran of the failed colonial war in Algeria was replacing a World War II survivor.

The French left Algeria in 1962, after a seven-year insurgency in which more than 1 million Algerians were killed and 1 million European settlers were driven from the country. But Algeria did not leave France. Several million Arab immigrants settled in France. And the bombing campaign in France, claimed by the Armed Islamic Group of Algeria, demonstrates that poisons brewed in the war for independence still circulate through both countries.

The latest terror attack on a Paris Metro train came on Tuesday, despite heavy police and military deployments in French cities triggered by a wave of bombings this summer. One accused bomber was tracked down and killed in September, but the terror campaign continues.

Ostensibly the Armed Islamic Group, which seeks a fundamentalist takeover of Algeria, is demanding that the French government halt its support for the Algerian military-dominat\ed government. Only then will the blasts stop.

But French support for the Algerian government is neither clear-cut nor decisive. Paris, along with the Clinton administration, has declined to provide helicopters or other equipment the Algerian government says it desperately needs to put down a savage civil war that has taken 40,000 lives since 1991.

The political effect of the bombings in France has been to harden French opposition to the Algerian Islamic movement, I sensed on a trip to France last month.

Then why bomb? The French play the role of not-so-innocent bystanders in this conflict. The war in Algeria is first and foremost a vicious power struggle between the fundamentalists and a now discredited military regime. But secondarily it is a war against French culture and education, against the legacies of the colonial era that favored Algerians who identified with France even after the French had gone.

Since late 1991, when the Algerian military refused to honor elections that would have given Islamic parties control of the National Assembly, the Islamic guerrillas have singled out for assassination teachers, civil servants, politicians and journalists -- the elite trained in educational institutions formed in the colonial era. The fundamentalists have also threatened to kill anyone who votes in Algeria's presidential election next month.

The military and police have fought back with brute force, fearing that loss or surrender will mean certain death for them. France fears being swamped by millions of refugees if Algeria collapses. The stakes in this drama, which the French thought was over for them 33 years ago, continue to mount.

Chirac's government has also been surprised by the international outcry over its decision to break a three-year moratorium on nuclear testing and stage two blasts at Mururoa Atoll, with five or six more to come, before signing a Comprehensive Test Ban treaty in 1996. France has joined China as the only major powers still testing.

Expert opinion is divided on the ecological dangers of this new testing for Mururoa, located 750 miles southeast of French-administered Tahiti. The French military make a strong case that these blasts are no more dangerous than the hundred-plus tests Mitterrand ordered conducted there before abruptly suspending them in 1992. It is the politics of testing, rather than the ecology of testing, that has changed. The halting of testing by the United States, Russia and Britain makes what was acceptable under Mitterrand unacceptable under Chirac.

The blasts in Mururoa remind the world of an anachronistic French control over territory far from home. The blasts in the subway in Paris remind the French themselves that colonialism's chickens come home to roost slowly. Both sets of blasts show how difficult it is to calculate the true costs a medium-sized, nuclear-armed nation-state pays to play a world role today.