(CNN) The US military has handed over 9,909 acres (4,000 hectares) of Okinawan land to Japan on Thursday in what's been lauded as the largest return of US-occupied land since 1972.

But there's a catch.

As part of the Treaty of Mutual Cooperation and Security between the two countries, the United States is granted the right to certain defense facilities. In exchange for the land, the Japanese government built several new helipads for the US military to use on its southernmost island of Okinawa.

Yet the handover has done little to assuage the ire of activists, who've campaigned for decades, to remove US bases altogether from Okinawa.

The American military presence is part of the U.S.-Japan Treaty of Mutual Cooperation and Security. American military have been present in Okinawa since the end of World War II.

The American military presence is part of the U.S.-Japan Treaty of Mutual Cooperation and Security. American military have been present in Okinawa since the end of World War II.

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

Many of the placards read "Withdraw Marine Corps," demanding the removal of American military bases.

Many of the placards read "Withdraw Marine Corps," demanding the removal of American military bases.

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

Organizers claimed this was the largest demonstration in Okinawa since 1995, when three Americans raped a local 12-year-old girl.

Organizers claimed this was the largest demonstration in Okinawa since 1995, when three Americans raped a local 12-year-old girl.

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

Crimes committed by American personnel have angered the Okinawa population for decades. Demonstrators held placards that read "our fury has gone beyond the limit."

Crimes committed by American personnel have angered the Okinawa population for decades. Demonstrators held placards that read "our fury has gone beyond the limit."

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

The protests followed the alleged rape and murder of a young Japanese woman by a former U.S. Marine employed as a civilian base worker.

The protests followed the alleged rape and murder of a young Japanese woman by a former U.S. Marine employed as a civilian base worker.

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

Tens of thousands of demonstrators rallied against U.S. military presence on the Japanese island of Okinawa on June 19, 2016.

Tens of thousands of demonstrators rallied against U.S. military presence on the Japanese island of Okinawa on June 19, 2016.

Mass protest in Okinawa against U.S. military bases after murder

Photos: Mass protest in Okinawa against U.S. military bases after murder

"We feel betrayed by the (Japanese) government," Takashi Kishimoto, a spokesman from an anti-US base activist group Peace Okinawa , told CNN.

"From our point of view, the US military (is) giving back something (it doesn't) want while having new Osprey runways built. Okinawa alone is host to 74% of the US's military bases in Japan. The return of this land only reduces this presence to 71%," he said.

Opposition to US military presence remains strong

The Northern Training Area, also known as Camp Gonsalves or the Jungle Warfare Training Center, is a 19,300-acre US installation in northern Okinawa.

The land has few buildings and roads and is home to several species of endangered animals. The partial handover of 9,909 acres of this area is part of a larger plan to return facilities south of Kadena and the Futenma base in the future. The United States occupied Okinawa until 1972.

The handover reduces the amount of US-controlled land on Okinawa by 17%, according to the US military.

"This decreased training area on Okinawa will not deteriorate our commitment or our ability towards working with the Government of Japan and our partners in the Japan Self Defense Force in mutual defense of this country," Lt. Gen. Lawrence D. Nicholson, commanding general of III Marine Expeditionary Force and Marine Forces Japan, said in a statement.

Nevertheless, some argue that the construction of the helipads in exchange for the land has further fueled anti-US military base sentiments among Okinawans.

"The problem is that these helipads have been constructed too close to residential houses, and they're aimed to deploy MV-22 Osprey (planes), which are hazardous to local people and the environment," Maki Kimura, a political scientist from University College London, told CNN.

US presence a sore point in relations

As part of a deal with Japan after World War II, the United States has roughly 26,000 troops and several bases in Okinawa.

The US presence has been a sore point in relations between the prefectural government and Tokyo as many Okinawans, including Takeshi Onaga, the prefectural governor, strongly object to accidents and alleged crimes attributed to the US military

In a handover ceremony Wednesday in Tokyo, Japanese Prime Minister Shinzo Abe expressed his desire to cooperate with the United States for regional peace and stability while reducing the burden of the US military presence on Okinawa.

Photos: Air Force CV-22 Ospreys take off from Kirtland Air Force Base, New Mexico, for a training mission. The Osprey is a tilt-rotor aircraft that combines the vertical takeoff, hover and landing qualities of a helicopter with the normal flight characteristics of a turboprop aircraft. Click through to see Ospreys in action. Hide Caption 1 of 11 Photos: A CV-22 Osprey, flown by the Air Force's 8th Special Operations Squadron, hangs in an anechoic chamber at the Joint Preflight Integration of Munitions and Electronic Systems hangar at Eglin Air Force Base, Florida, in 2012. Hide Caption 2 of 11 Photos: An MV-22 Osprey from Marine Medium Tiltrotor Squadron 262 soars over the Pacific Ocean during a flight from the Philippines to Australia in 2014. Marines and aircraft from VMM-262, VMM-265 and Marine Aerial Refueler Transport Squadron 152 flew approximately 4,700 miles from Okinawa, Japan, to Brisbane, Australia, to provide aerial support for President Barack Obama and Marine Helicopter Squadron One during the G20 Summit. When paired with the KC-130J tanker, the Osprey can provide assault support anywhere in the 105 million square miles that make up the Marine Forces Pacific area of responsibility. Hide Caption 3 of 11 Photos: A CV-22B Osprey receives fuel from an MC-130H Combat Talon II on June 21, 2013, off the coast of Greenland. Hide Caption 4 of 11 Photos: Sailors assigned to the aircraft carrier USS George Washington (CVN 73) and Marines assigned to the 3d Marine Expeditionary Brigade load boxes of supplies into a U.S. Marine Corps MV-22 Osprey from Marine Medium Tiltrotor Squadron (VMM) 262 to be airlifted to nearby villages during relief efforts after Supertyphoon Haiyan. Hide Caption 5 of 11 Photos: Sailors aboard the amphibious transport dock ship USS Mesa Verde (LPD 19) stow an MV-22 Osprey in the hangar bay. Hide Caption 6 of 11 Photos: A Marine MV-22 Osprey makes contact with a KC-10 Extender tanker's drogue from Travis Air Force Base off the coast of San Francisco at 10,000 feet in October 2014. Hide Caption 7 of 11 Photos: An MV-22B Osprey, assigned to Marine Medium Tiltrotor Squadron 365 (Reinforced), 24th Marine Expeditionary Unit, hovers over the flight deck of the amphibious transport dock USS New York, at sea, in January 2015. Hide Caption 8 of 11 Photos: U.S. Marines with Special-Purpose Marine Air-Ground Task Force Crisis Response-Africa board an MV-22 Osprey during an alert force drill at Moron Air Base, Spain, on March 13, 2015. The alert force tested its capabilities by simulating a reaction to a real-time crisis response mission by flying to Sigonella, Italy, on a moment's notice. Hide Caption 9 of 11 Photos: Sailors and Marines prepare to launch MV-22 Osprey tilt-rotor aircraft assigned to Marine Medium Tiltrotor Squadron (VMM) 262 (Reinforced) from the flight deck of the amphibious assault ship USS Bonhomme Richard (LHD 6). Hide Caption 10 of 11 Photos: Combat controllers from the 21st Special Tactics Squadron fast-rope from a CV-22 Osprey during Emerald Warrior near Hurlburt Field, Florida, on April 21, 2015. Emerald Warrior is the Department of Defense's only irregular warfare exercise, allowing joint and combined partners to train together and prepare for real-world contingency operations. Hide Caption 11 of 11

But in Okinawa, sentiments remain divided, with the Okinawa prefectural governor announcing his refusal to attend the handover ceremony in a statement released earlier this month.

"This handover isn't enough," Kouji Ida, the deputy councilor from the Okinawa prefectural government's military base affairs division, told CNN.

"The helipads will be used to launch Ospreys, and we fear there may be more crashes. Ultimately, we hope the presence of the US military bases will continue to shrink," Ida said.

It's important to understand the context surrounding the deal, according to Gavan McCormack, an emeritus professor and Asia expert at the Australian National University.

"The whole of Okinawa is an American military base, and there's deep anger there as the Okinawans don't feel like the bases are there for their defense," McCormack told CNN.

"The people aren't only concerned by the noise pollution caused by the Ospreys but the danger to life and limb."