CAMP FOSTER, Okinawa — Two Japanese senior citizens sat through the second day of a hunger strike near the Marine Corps headquarters on Okinawa on Thursday to oppose the planned deployment of Osprey aircraft to the island.

Seishin Uehara, 85, and Tomoyuki Kobashigawa, 69, are drinking only water and using a portable toilet while spending their time under a makeshift tent on the public sidewalk outside a Camp Foster gate.

The planned fall deployment of the Marine Corps’ new hybrid aircraft has sparked deep controversy over safety in Japan and would “add further danger and constant fear of a crash” to the daily lives of Okinawa residents, Kobashigawa said.

The two men said a hunger strike might be a risk to their health but is meant to demonstrate how deeply the Okinawans oppose plans to replace the aging Marine Corps Sea Knight helicopters at the Futenma air station with two squadrons of Ospreys.

A team of Japanese investigators traveled to North Carolina and the Pentagon this week to review the aircraft’s safety record, including a recent crash that killed two Marine crew members in Africa. The U.S. has said it will not begin flying the Ospreys here until Japan is satisfied the aircraft is safe.