Approximately 1,000 people participated in a sit-in protest against the continued construction of a planned U.S military air base located on the outskirts of Nago, a city on the Japanese Island of Okinawa.

To mark the 500th day of protests, an increased number of revellers gathered in front of the U.S. Marine Corps Camp Schwab in an attempt to block construction vehicles from entering the area, with some protesters shouting "stop the relocation work" and holding signs that read "Marines out," according to local media reports.

Hiroji Yamashiro, a 63-year-old protester, said that their fight to block the construction has “reached a critical point.”

While another member of the demonstration, Kazue Shimabukuro, 73, lost her father in the Battle of Okinawa, in a bloody ground battle between Japan and the U.S.-led Allied forces during World War II that claimed the lives of 82,000 civilians and military personnel. She told local reporters that she has “no doubt” the permit given to the U.S. Army to build a new base will be revoked.

Find out why we stand with the grandparents of Okinawa #SavetheDugongs #HenokoNow https://t.co/PgZZ91fAEE pic.twitter.com/A3ewtOffIt

— GP Rainbow Warrior (@gp_warrior) November 13, 2015

The 500th day of protesting came a day after the central government of Japan filed a lawsuit with the Naha branch of the Fukuoka High Court, demanding that Okinawa Governor, Takeshi Onaga, officially retract his decision to grant permission to the U.S Army to build a new air base on the island.

The sit-in protest started July 7 2014 and has attracted protesters from the immediate area and mainland Japan with participants ranging from students, scholars, artists and even politicians.

OPINION: Japan’s Right to Renounce War

Local surveyssuggestthat 76.1 percent of the Okinawaresidents are against the construction of the air base which is due to be a replacement for the U.S. Military'scurrentFutenma base, also on the island of Okinawa.

The U.S. has been looking to move from its Futenma location after the gang rape of a local schoolgirl by U.S. servicemen in 1995.

Asidefromraisingmemories of previousconflictswith the U.S. the proposed base’s immediate area is the habitat of the endangered marine mammal the Dugong, an animal synonymouswith the island.

Locals have resisted US military base expansion for 500 days, support them, #SaveTheDugongs https://t.co/ExivvH1FVi pic.twitter.com/icxU2n3TBm

— Greenpeace (@Greenpeace) November 18, 2015