TOKYO » Wearing gas masks and baggy gray suits, a special U.S. Marine Corps unit trained to rescue people in chemical, biological or nuclear emergencies held drills Saturday with Japanese counterparts, standing ready to help out if needed around the crippled Fukushima Dai-ichi nuclear plant.

The 145-member Chemical Biological Incident Response Force, based at a naval support facility in Indian Head, Maryland, near Washington D.C., flew to Japan on April 2 to offer its assistance to Japan, officials said.

It is the unit’s first overseas deployment, but it does not signal heightened alarm in Washington about the Fukushima Dai-ichi plant, members said. It also has no plans to go north, closer to the nuclear plant, where operators are trying to bring reactors under control after their cooling systems were knocked out by last month’s tsunami.

"We’re here to solve a complex problem if called upon," said mission commander Maj. Mike Johnson.

The noncombat unit will be based indefinitely at Yokota U.S. Air Force base, just west of Tokyo.

"We’re here to assist and advise the Japanese military and to be a quick reaction force if something really, really bad does happen. All indicators say it’s not going to, but it’s better to have us and not need us than to need us and not have us," said Master Sgt. Mark Dumdie, 40, the most senior enlisted man in the outfit.

The unit arrived with 32 vehicles and piles of high-tech equipment carried on seven planes. One vehicle is a mobile laboratory where staff can quickly analyze substances and another can fire a laser into a plume of smoke that can detect toxins in it, said Dumdie, who comes from Copperas Cove, Texas.

In a demonstration to journalists, Marines and sailors rescued mock victims who may be exposed to chemicals or radiation, extracting them from an overturned car and the top of a three-story building and whisking them to a makeshift decontamination tent. There Marines in full body suits cut off the outer clothing of the victims and sprayed some off with water and scrubbed others down with soap and water.

Other victims who pretended to be injured were rushed to a medical tent where doctors and medics attended to them.

"When we show up, we can do everything from pulling people out of a rubble pile to decontaminating to medical assistance," Dumdie said. In the medical tent, "we can do everything short of open heart surgery."

Covered in white suits, members of the Japanese military’s own nuclear, biological, chemical defense unit participated in drills, spraying down a vehicle to clean it of imaginary nuclear contamination. Japan has sent about 400 members of this 1,000-member force to near the Fukushima plant, according to Col. Hiroki Ushijima of Japan’s Self-Defense Force.

"We’re working together (with the Japanese) in scenarios like this and others to make sure we can be seamless in case we’re called upon," said Johnson.

The CBIRF unit was created in 1996 in the wake of the 1995 sarin gas attack on the Tokyo subways so that the U.S. could respond effectively to similar crises, Dumdie said.

The unit was deployed during the 2001 anthrax attacks that killed five people through exposure or inhalation of letters containing the substance, he said. Team members took samples from the letters, and bagged and burned them.