Japan's lower house on Thursday adopted a resolution urging the government to reduce the burden on Okinawa in hosting the bulk of U.S. forces in the country, in a move that marks the 50th anniversary of the southern island prefecture's reversion to Japanese rule.

The resolution was adopted at a time when defense experts fear for the security of the base-hosting prefecture amid increasing challenges facing the Japan-U.S. alliance in light of situations such as cross-strait tensions between Taiwan and China and the ongoing Ukraine war.

The House of Representatives also called on the government to make utmost efforts to turn Okinawa into a stronghold for global peace and stability.

In a lower house plenary session after the resolution was adopted, Prime Minister Fumio Kishida vowed to "make tangible progress in reducing the base-hosting burden" on Okinawa in consideration of the feelings of local residents, while maintaining the deterrence capability of the Japan-U.S. alliance.

Okinawa remained under U.S. occupation until May 15, 1972, even after Japan restored its sovereignty after its defeat in World War II based on the 1952 San Francisco Peace Treaty.

But the prefecture still hosts around 70 percent of total acreage exclusively used by U.S. military facilities in the country, despite only representing 0.6 percent of the country's total land area.

Okinawa is seen as strategically important given its proximity to North Korea, which continues to alarm Japan due to its ballistic missile tests and nuclear development, as well as to the Japanese-administered, Chinese-claimed Senkaku Islands in the East China Sea. Okinawa is also near Taiwan.

In the resolution adopted by a majority vote by the ruling and opposition parties, the lower house called for the local economy to be revitalized as part of a national strategy, referring to how Okinawa's average income per capita was the lowest among Japan's 47 prefectures.

"The government, parliament and prefecture should unite in promoting comprehensive, drastic and sustainable measures" to shore up Okinawa's development, the resolution said. The lower house also called for nurturing talent in the arts and education.

On May 15, Japan will hold ceremonies in Tokyo and Okinawa simultaneously to mark 50 years since the reversion, the government said.

Both at sea and on land, local residents also commemorated on Thursday the 70th anniversary since the treaty took effect. April 28 is widely regarded in Okinawa as a "day of insult."

Earlier in the day, around 20 boats sailed from Kunigami on the northern tip of Okinawa and from Yoron, on the southern tip of Kagoshima Prefecture, to recreate a scene reminiscent of protests in the 1960s calling for the reversion of Okinawa. The participants sang a song popular at the time seeking the return of Okinawa.

The Amami islands including Yoron remained under U.S. control until 1953, a year after the treaty took effect, and boats frequently sailed in the 1960s to the waters between Yoron and Okinawa to rally for the reversion of Okinawa.

Around 70 people also held a rally in front of the Okinawa prefectural office, protesting against the government's push to move forward with a plan to relocate the U.S. Marine Corps Air Station Futenma without heeding public will.

The protestors carried a banner calling for Okinawa to be a "peaceful island without military bases."

Tensions between the central government and Okinawa remain high as the government continues to move ahead with the Futenma relocation plan, which has been stalled as residents remain divided over the issue.

Japan and the United States have been pushing to have the Futenma base, located in a residential area of Ginowan, relocated to the less populated coastal area of Henoko in Nago.

Hosting U.S. bases remains a contentious issue in Okinawa amid incidents involving U.S. servicemen over the years as well as increasing regional and international security concerns.

Related coverage:

News photo exhibition showcases 50 yrs since Okinawa return to Japan

55% of Okinawans unhappy with 50 yrs since reversion to Japan: poll