CNN  — 

United States military personnel on the Japanese island of Okinawa are on virtual lockdown after almost 100 cases of coronavirus have emerged on several US Marine Corps bases there.

The lockdown order, which was issued Saturday morning, bans almost all off-base movement by the tens of thousands of US military personnel on the bases unless approved by an officer with the rank of lieutenant colonel or above.

The order includes the vital Kadena Air Base, which bills itself the hub of US air power in the Pacific, and comes after US admirals last week touted the “extraordinary measures” the Navy had taken to restore US military readiness in the region in the face of the worsening pandemic.

The US Marine Corps Air Station Futenma in Ginowan in Japan's southern island prefecture of Okinawa.

The Okinawa prefectural governor’s office said 94 cases of Covid-19 have been diagnosed among the personnel at the US Marines Corps’ Air Station Futenma, Camp Hansen and Camp Kinza as of Monday afternoon.

Maj. Kenneth Kunze, communications strategy and operations officer for the US Marines in Okinawa, confirmed the numbers provided to the Okinawa government were accurate and said contact tracing was underway on the island to see if there were any more cases. Hundreds of Marines and their family members were being tested, he said.

A statement from US Air Force Brig. Gen. Joel Carey, the commander of Kadena Air Base, on Friday said “multiple new positive cases” had emerged on US military facilities on the island as well as three cases among the local population.

“The US cases have primarily been Marines assigned to MCAS Futenma and Camp Hansen, and have been a mix of both travel related and those with origins we’ve yet to be able to identify indicating the potential of a reemergence of community spread,” Carey’s statement posted on the base’s website said.

Kunze said any travel-related cases would have come through Kadena on a flight from Seattle, which also stops at US military bases in Yokota and Iwakuni, Japan. But as of Monday afternoon Japan time, no Covid-19 cases had been reported on Kadena.

The recent infections of Marine personnel are the first the service has seen on Okinawa since the outbreak of the virus earlier this year.

US Marine Corps bases were put under Health Protection Condition Charlie, which, according to a Marine website, bans any off-base activity except traveling to and from the bases to residences. Any other travel requires the approval of a senior officer.

US Marines trains at Camp Hansen, Japan, in 2017.

US Marine personnel and their families, including US civilian contractors, are not permitted to visit any off-base establishments, use public transportation, or even exercise outdoors, under Condition Charlie. Personnel may also not take any leave or vacation time.

The Kadena Air Base Facebook page said it also was under Health Protection Condition Charlie, but the Air Force restrictions were slightly less stringent than those issued by the Marines, allowing visits to off-base grocery stores, pharmacies and food drive-thrus.

Despite the restrictions, Okinawa government officials expressed frustration with the US forces.

In a statement, Prefectural Gov. Denny Tamaki said the US should not be allowing troops to come to Okinawa from bases in the US and elsewhere during the pandemic.

The governor’s office said US military personnel arriving on the island were being housed in hotels in the Chatan district of the island, near Kadena Air Base because on-base facilities were filled with US personnel in Covid-19 isolation.

Kunze said Monday that all Covid-19 cases were in isolation in US Marine barracks on the island.

Additionally, all Marines, their family members and US civilian workers arriving on the island face 16 days in quarantine, he said.

Tamaki told public broadcaster NHK News that the surge in US cases comes after the island had done well preventing coronavirus cases.

“I am shocked. It is extremely regrettable that a large number of cases are occurring in a short period of time at a time when all Okinawans are trying so hard to prevent the infection from spreading,” he said.

Okinawa had zero new cases between May 1 and July 7. Total number as of July 10 is 145 infections, which includes seven deaths.

NHK reported Saturday that three visitors to Okinawa from the Tokyo area had tested positive for Covid-19 since last Thursday.

The Japanese capital and the country as a whole have seen surging cases of Covid-19 for the past week. On Sunday, 411 new cases were reported across the country, 206 of those in Tokyo, the fourth day in a row it had seen more than 200 new cases.

The new cases among US military members come as the virus is also spreading rapidly in the United States. More than half of the country’s 50 states are dealing with increased rates of new cases compared to a week ago.

One state, Florida, reported 15,299 new Covid-19 cases on Saturday, the highest number of new cases in a single day by any state since the coronavirus pandemic began.

But in the Pacific, the US military has said it has been successful in combating the virus, which left the aircraft carrier USS Theodore Roosevelt crippled for weeks in the spring when the virus struck more than 1,000 members of its crew.

A U.S. Navy P-8A Poseidon takes off  Aug. 10, 2018, from Kadena Air Base, Japan.

Last week, however, two of its sister ships, the USS Ronald Reagan and USS Nimitz, completed rare dual-carrier exercises in the South China Sea. The admirals in charge of those exercises said the Navy had gone to “extraordinary measure” to achieve a high level of readiness.

“The entire team underway, everyone on board, is required to wear a mask,” Rear Adm. George Wikoff, commander of the Reagan carrier task force, said of the 12,000 personnel in the exercises..

The Navy has also spaced out mealtimes, instituted social distancing and brought aboard specialists including microbiologists and extra health personnel, said Wikoff.

But a worsening Covid-19 situation on Okinawa could set back US efforts in the Pacific.

Kadena bills itself Keystone of the Pacific. Almost 18,000 Americans work on the base, which hosts US Air Force fighter jets, US Navy reconnaissance planes and its a major hub for US aircraft movement throughout the region, including frequent operations over the South China Sea.

Meanwhile Monday, US Forces Korea reported Monday that 11 US service members arriving in South Korea had tested positive for Covid-19. All personnel entering South Korea are tested and quarantined for 14 days, USFK said in a tweet.

CNN’s Ivan Watson and Rebecca Wright contributed to this report.