The number of U.S. Marines in Okinawa may fall to around 14,000 for a prolonged period, as some 3,000 troops who are to leave for Iraq may not return to the island prefecture, a source close to Japan-U.S. relations said Saturday.

The number of U.S. Marines in Okinawa currently stands at about 17,000. The U.S. Defense Department has already said it has no plan to send replacements to Okinawa after 3,000 Marines leave for a seven-month deployment in Iraq. They will be sent to Iraq in batches from February through April.

One of the options the Pentagon is considering is to send the 3,000 troops back to their original U.S. bases or move them to other overseas bases after their mission in Iraq is completed, the source said.

If that step is taken, the number of marines in Okinawa would stand at 14,000 for the time being, although it is uncertain how long that situation will continue, it said.