Things seem to be getting worse in Japan right now. In the aftermath of a 9.0 earthquake, a massive tsunami and a nuclear power plant on the verge of meltdown, the US has urged any American citizens to evacuate Japan.

The State Department says the first U.S. evacuation flight has left Japan Thursday and heading to Taiwan with about 100 people on board.

Officials also warned U.S. citizens to defer all non-essential travel to any part of the country as unpredictable weather and wind conditions risked spreading radioactive contamination from Friday's magnitude 9 earthquake and subsequent tsunami.

The travel warning extends to U.S. citizens already in the country and urges them to consider leaving. The authorized departure offers voluntary evacuation to family members and dependents of U.S. personnel in Tokyo, Yokohama and Nagoya and affects some 600 people. The U.S. also urged Americans within 50 miles of the crippled Fukushima Dai-ichi nuclear plant to relocate.

Officials defended the proposed evacuation zone for American troops and citizens in Japan.

"I want to stress this is a prudent and precautionary measure to take," Gregory Jaczko, chairman of the Nuclear Regulatory Commission, told a White House briefing. The evacuation zone recommended by the U.S. is far wider than that established by Japan, which has called for a 12-mile zone and has told those within 20 miles to stay indoors.