On the Monday after Thanksgiving, a package about the size of a shoebox arrived at the Women's Feminist Health Center in Portland, Ore. It carried a Portland postmark. The center has been the target of threats, vandalism and frequent demonstrations by antiabortionists, and workers have been trained to watch for suspicious packages and envelopes. They called the police, who defused a bomb that a police spokesman said was powerful enough to kill.

Police defused three similar bombs in packages at Portland's main post office. One package was addressed to Dr. Peter Bours of suburban Forest Grove, who was the topic of a major magazine article recently on the harassment he was getting for performing abortions. He is a member of the board of Oregon's chapter of the National Abortion Rights Action League. Another package was addressed to the Lovejoy Surgicenter in Portland, where abortions are performed, and the third to a Planned Parenthood clinic, which does not perform abortions, but which dispenses contraceptives.

"To our knowledge, it's the first time there's been a letter bomb," said a NARAL spokeswoman.

She also said clinic bombings resumed in October, with little or no media coverage. She cited four incidents: On Oct. 30, the Delta Women's Clinic in Baton Rouge was burned to the ground by arsonists, and another clinic was burned. On Oct. 26, the Hallmark Clinic in Charlotte, N.C., was the target of arsonists, and on Oct. 19, the Coram Women's Center in Suffolk County, N.Y., was bombed.

"We consider it terrorism," said the NARAL spokeswoman. "We consider it legitimate news. This is very, very serious."

Indeed, it is. On Dec. 10, the Manhattan Women's Medical Center was bombed. A NARAL spokeswoman said the incident occurred in midafternoon while procedures were being performed. She said someone called the police emergency number and asked them to evacuate the clinic. Then police got a second call and were told the clinic was not being evacuated fast enough. Shortly thereafter, a bomb went off in a second-floor bathroom. Damage was not extensive, she said, and no one was injured, although a receptionist was still in the building.

"You're torn between hoping this is an isolated nut in Oregon and the memory of what was happening this time of year a year ago," said Nanette Falkenberg, executive director of NARAL. "Is this a re-escalation of what was going on?" There were at least 24 bombing or arson attacks on abortion facilities in 1984, with the attacks increasing in frequency and severity during the Christmas season, prompting President Reagan to order an all-out federal effort in early January to find those responsible. He did not, however, order the FBI to take over the investigations, which have been the responsibility of the Bureau of Alcohol, Tobacco and Firearms. The FBI investigates bombings when terrorist groups are suspected.

"Two things are different about the Oregon and Manhattan [incidents]," Falkenberg said. "Both involved tactics we haven't seen before. They were both clearly targeted to hurt people in the clinics. Before, they [the bombs] went off at night," when the clinics were empty. "In Manhattan they called, but it came very close to having people in the clinics."

She said the Oregon NARAL affiliate had called for a moratorium on picketing at clinics through the New Year to "tone down the level of debate" during the season but that the suggestion had been declined.

"I think as you increase the tone and level of hysteria around the issue, as you push the edge of the mainstream of a movement, the people who are already on the fringe, it gives them permission to move further and further out," said Falkenberg.

Her explanation for the turn to violence against the clinics that has occurred in the past couple of years makes sense. Prochoice organizations have documented numerous incidents of harassment outside clinics and of people who work in clinics. Peaceful dissent has given way to threats and intimidation. In Fairfax County, for example, antiabortionists are trying to organize a boycott of Fairfax Hospital and have urged sympathizers not to donate to its blood bank in an attempt to stop abortions from being performed at the hospital. This is nothing less than an attack on the community's blood bank.

Extremism has bred fanaticism, and with the incidents in Oregon and Manhattan it has bred terrorism. Before somebody gets killed, we had best be willing to recognize that this is what we're dealing with now, and address the problem as the threat to the social order that it is.