The Japan Coast Guard said Tuesday it believes the four Americans reported missing at sea near Okinawa since Sunday may still be alive, and guardsmen are searching for an inflatable raft the men may have used to escape the 66-foot yacht they were sailing in during Typhoon Jangmi.

Debris and the radio transmitter from the "Jade Princess" were found Sunday evening near the Okinawa prefectural island of Ishigaki about six hours after the Japan Coast Guard received a radio distress signal, said Japan Coast Guard spokesman Takamichi Higa.

The four have not been identified.

The U.S. Coast Guard said it is monitoring the rescue efforts, but is not involved in the search.

Two patrol ships and three rescue planes continue to scour the waters despite stormy weather, Higa said.

Okinawa’s warm water temperatures might give the men a higher chance of survival, he said.

Stars and Stripes incorrectly reported in Wednesday’s edition that the men had planned to board a cruise ship in Yokohama in mainland Japan. Higa said the Americans were ultimately going to sail to Yokohama, with plans to stop in Okinawa first.

The passengers encountered the storm a week after leaving a Malaysian port on Sept. 21.

Higa said the Japan Coast Guard prohibited sailing or cruising in Japanese waters during the typhoon, but had no jurisdiction on imposing similar restrictions in international sea territories.

Higa said the Japan Coast Guard received a radio distress signal from the yacht Sunday morning about 62 miles southwest of Ishigaki.

Attempts to reach the yacht by maritime telephone were unsuccessful, prompting search-and-rescue efforts.

By that afternoon, winds from the typhoon had reached nearly 80 miles per hour, Higa said, preventing patrol ships from immediately entering the area.