Pentagon weighs pullout from Japan hot zone

THE PENTAGON - The Defense Department was considering Monday night ordering the mandatory departure of all American military personnel and their families from the areas of Japan threatened by radiation, CBS News national security correspondent David Martin reports.

The government considered such an order after distributing potassium iodide pills, which defend the body from radioactive iodine, to service members of the USS George Washington and their families left ashore after the nuclear-powered aircraft carrier abruptly left Yokosuka, Japan, Monday morning.

Complete Coverage: Disaster in Japan
Carrier leaves Japanese port to dodge radiation

The George Washington got underway not to aid in the relief effort but to save itself from radioactive contamination.

The decision to send the George Washington to sea, even though one of its nuclear reactors is down for repairs, came in response to a shift in the wind, which is now blowing increased amounts of radioactivity south over Tokyo toward the American bases at Yokosuka and Atsugi. The winds threaten to dump as much radioactivity in the next 24 hours as in the preceding 10 days.

Navy officers decided they could not allow the George Washington to keep absorbing even low levels of radioactive contamination for the indefinite future. At $4.5 billion, it is one of the Navy's most valuable ships, and the fear is that radiation would be sucked into the ventilation system and leave it contaminated for the rest of its service life.

The situation in Japan has been a fight around the clock to get try and get control of the damaged nuclear power plant north of Tokyo crippled by the earthquake and tsunami that left more than 8,800 people dead.

Workers were forced to evacuate again Monday after smoke was spotted coming from two of the reactors.

There were new concerns Monday night about radiation detected in Japanese crops and in seawater near the plant.