More U.S. military crews were exposed to radiation Tuesday as they ramped up relief flights over Japan, and Americans on two military bases south of Tokyo were advised to stay indoors as much as possible.

Meanwhile, U.S. aviation and energy officials also worked with Japanese counterparts on the nuclear crisis set in motion by last week's earthquake and tsunami in northeast Japan.

With more aid for victims on the way, the U.S. Navy said it was redirecting three ships to work in the Sea of Japan on the country's west coast rather than risk the hazards of radiation and the debris field in the waters off the east coast.

Sensitive air monitoring equipment on the aircraft carrier USS George Washington detected low levels of radioactivity from the Fukushima Dai-ichi nuclear power plant as the carrier sat pier-side at Yokosuka, Cmdr. Jeff Davis, a spokesman for the U.S. 7th Fleet, said Tuesday.

While he said there was no danger to the public, the commander recommended military personnel and their families at Yokosuka and Naval Air Facility Atsugi limit their outdoor activities and seal ventilation systems at their homes as much as possible.

The Navy said Monday that radiation was detected by another carrier, the USS Ronald Reagan, and that 17 helicopter crew members had to be decontaminated after returning to the Reagan from search and rescue duty. The Navy said more crews were exposed to very low levels of radiation Tuesday and had to be decontaminated.

The Reagan strike group — which includes seven other ships — flew 29 missions Tuesday to deliver 17 tons of food, water, blankets and other relief supplies ashore.

"We continue to monitor the winds closely, moving our ships and aircraft as necessary to avoid the wind line from the Fukushima power plant," Davis said. "Our aircraft and aircrews returning from missions ashore are being monitored carefully for contamination, and we are conducting decontamination procedures as necessary when it is detected."

A three-ship amphibious group, including the 31st Marine Expeditionary Unit aboard the USS Essex, was directed to position itself in the Sea of Japan and was to arrive Thursday for other relief duties.

Meanwhile, Energy Secretary Steven Chu said his department has assembled a team of 34 people and sent 7,200 pounds of equipment to Japan to help monitor and assess the situation with the nuclear reactors.

And the Federal Aviation Administration said the United States is working closely with Japan to ensure that problems associated with a stricken nuclear power plant do not jeopardize air travel safety. Spokeswoman Laura Brown said the Japanese civil aviation authority "has established flight restrictions keeping civil aviation flights away from the Fukushima facility" and said U.S. airlines have indicated they are complying with the new rules.

"There is no credible information available at this point indicating the need for further restrictions," Brown said in a statement Tuesday, adding that if the situation worsens the FAA is prepared reroute air traffic or take other measures.