Turkey's extreme right-wing Nationalist Action Party recently decided to bulletproof the cars of its top officials. The party's own private bodyguards contacted an Istanbul businessman who owned the country's only bulletproofing plant, drove him to a firing range in one of his armorplated cars, pulled out their machine pistols, and asked him to sit behind the wheel while they had a go at him.

"He refused," said one of the bodyguards with a smile. "So I told him to bulletproof our cars so he would not refuse."

The guards had every reason to be meticulous. Turkey is suffering from a plague of political violence. Nationalist Action Party members are among the principal targets -- and targeters -- in an undeclared civil war.

The extreme left is splintered into innumerable groups. Embracing many shades of Marxism. But the extreme right-wing terrorists are united behind the ideology of the Nationalist Action Party and are loyal to Alparslan Turkes, its chairman.

The Mercedes owned by Gun Sazak, the Nationalist Party's deputy leader, was not bulletproof but would not have saved him even if it had been. The terrorists who hid among the chestnut trees near his home in Ankara last May waited until he got out. They shot him as he was unloading a picnic basket from the trunk. The politician, 47, did not have time to draw his own pistol. He died on the way to the hospital.

Less than two months after Sazak's murder, Moslem activists loyal to the party attacked the Alawite left-wing minority in Corum, a Turkish market town of 70,000 people. Nearly 30 people, most of them Alawite Moslems, were slain in the ensuing riots.

In two separate attacks last week, unidentified terrorists assassinated former prime minister Nihat Erim and Abdurrahman Koksaloglu, a social democratic deputy belonging to the main opposition Republican People's Party of former prime minister Bulent Ecevit.

Koksaloglu was the first member of parliament to have become a terrorist target and his and Erim's deaths represented a serious escalation of the violence. After targeting students, professors, journalists, prosecutors, judges, provincial politicians, policemen and soldiers, terrorists now have turned their guns on national political figures.

For most of the 1960s and 1970s, Turkes was the sole representative of his party in parliament. A severe man, he always dressed in dark clothes.

In the eyes of the left and Ecevit, Turkes is no better than a Hitler or a Mussolini. For his part, however, Turkes says it is simply a universal trick of communists to label nationalists as fascists.

Turkes' young followers are called commandos or Gray Wolves.

The Gray Wolves hark back to the beast that that in a legend led Turkish tribes from the famine-stricken steppes of Central Asia to a new homeland in Asia Minor.

The modern Gray Wolves were originally young men trained in armed combat and indoctrinated with party nationalism in secret camps in the countryside, then unleashed onto university campuses to counter increasingly extreme left-wing influences. What started as a battle for the domination of the campuses turned into a struggle for the control of the country.

The Nationalist Action Party's fortunes changed dramatically when Turkes became deputy prime minister in the Suleyman Demirel coalition and turned from an oddity into a formidable political power.

Turkes' deputy premiership gained the party a say in the country's affairs far beyond it parliamentary strength or popular support. At the same time, the party secured a foothold in the bureaucracy and police and extended its patronage.

In 1977, Turkes won 16 seats in the 450-member ruling National Assembly and the Nationalist Action Party became the country's fourth-largest party. It is now the principal power keeping Demirel's right-wing minority government in office. But Turkes and his party have more strength and importance than their numbers in the assembly might suggest.

Violence, disruption of state authority and economic depression of recent years have enhanced the appeal of radical nationalism and discipline for the ever-growing number of poor Turks.Unprotected by the state in the ever-present and escalating violence, many people are beginning to turn to Turkes and his army of armed militants for security.

Demirel has permitted the party to become a state within a state, even with the knowledge of its role in political violence. It appears Demirel does not care how strong the Nationalist Action Party grows because it is anti-communist.

A nationalist official said the party expected a 150 percent increase in its share of the vote next year and 40 more seats. Some analysts find that estimate conservative.