WASHINGTON (AP) — Transportation Secretary Norman Mineta said Wednesday there have been 400 reports of lasers being beamed at airplanes since 1990 and the Federal Aviation Administration will now require pilots to immediately report such incidents to air traffic controllers, who will be required to notify law enforcement officials.

The lasers can temporarily blind pilots. A cluster of incidents received wide attention between Christmas and New Year's Day. Authorities believe copycats who have heard news reports about the lasers apparently have been involved in some of the more recent incidents.

Mineta said in a news conference at the FAA's aeronautical research center in Oklahoma City that 31 of these incidents have been reported since Dec. 31, including one Tuesday night in Phoenix, Ariz. Nobody was arrested in that incident, which involved a Southwest flight. The new reporting requirements take effect Jan. 19.

There is no indication that people shining lasers at airplanes had terrorist motivations, Mineta said.

"Shining these lasers at an airplane is not a harmless prank," Mineta said. "It's stupid and dangerous. You are putting other people at risk and law enforcement authorities are going to seek you out and if they catch you, they are going to prosecute you."

Mineta said officials are working on possible devices to protect pilots from lasers, including possible modifications to windshields, but no one solution has emerged. Research into the issue is being done at the aeronautical center.

He also said an effort will be made through government regulatory agencies to ensure that laser devices are better labeled to warn about the dangers of using them improperly.

A wide range of people are believed to have been behind the incidents, Mineta said.

"Stupidity is not something monopolized by any age, or sex," he said.

Terry McVenes, executive air safety chairman for the Air Line Pilots Association, the biggest pilots' union, said in a telephone interview that pilots are on board with Mineta's plan.

"We're very happy with what the secretary has done here," McVenes said. "It does provide a means of collecting data so we can assess what the threat really is, or if there is a threat."

McVenes said the recent laser incidents are a safety issue as well as a potential security threat:

"It's a safety issue in the fact that something is being introduced into the cockpit that causes us some concerns. It could be a security issue if we find out it's part of a terrorist threat. At this point we don't know if it's just some isolated cases of jokes and pranks or part of an organized effort."

"The whole idea of having this reporting system is a good one so they can use the data to figure out exactly what we do have."

The Coalition of Airline Pilots Association issued a statement expressing concern over laser incidents.

"Pilots have already experienced the dangers posed by laser attacks, and terrorist use can not be ruled out," association president Jon Safley said. "We're very concerned about the amount and quality of information getting to pilots about this growing problem, and we applaud the FAA's initiative."

Last week, a pilot told law enforcement officials that a green light appeared on the nose of his aircraft as it was taking off from the Burbank, Calif., airport.

"To our knowledge there was no danger to the aircraft," said Cathy Viray, spokeswoman for the FBI in Los Angeles.

Last weekend, two pilots near Washington Dulles International Airport reported lasers beamed at them, according to FBI spokeswoman Debra Weierman.

The first incident occurred Saturday and involved a helicopter from the Fairfax County (Va.) Police Department; the other happened Sunday to a US Airways Express flight.

Weierman said the bureau was investigating. There have been no arrests and neither pilot was affected by the laser light, she said.

In Boise, a pilot told the FBI that someone was possibly using a red laser on a small plane shortly after takeoff Friday evening, according to Dominic Venturi, the FBI supervisor.

"It did not injure the pilot or any of the passengers on board," Venturi said, adding the FBI believes it has identified the person responsible.

"We feel confident it is not related to terrorism," he said.

Beginning Christmas night, there were reports of lasers pointed at aircraft cockpits in Cleveland, Houston, Colorado Springs, Medford, Ore., and Nashville Many of the reports described a green beam.

A New Jersey man was arrested and charged last week for aiming a green laser at a small jet flying over his home near Teterboro Airport.

The man, David Banach of Parsippany, said he had been using the device to point at the stars from his back yard.

That type laser pointer, which sells for $119, is the most powerful that can be used in a public place without government regulation, according to Bigha, the company that manufactures it. It produces a bright green beam that can be seen up to 25,000 feet away, and is used by bird watchers, astronomers and lecturers to point out faraway objects.

The FBI and Homeland Security Department sent a memo to law enforcement agencies in November saying they had evidence terrorists have explored using lasers as weapons.

An FAA report released in June found that even the lowest-intensity lasers temporarily impaired the vision of most of 34 pilots who were studied in a flight simulator.