After two deadly air accidents in recent weeks, the Marine Corps on Friday ordered all its aviation units to briefly ground their aircraft, review the safety of their operations and study past failures to glean lessons from them.

The safety measure affects about 50 helicopters and tilt-rotor Ospreys at Kaneohe Bay — 13 of which deployed to northern Australia in the spring for a six-month rotation. The stand-down also applies to the base’s RQ-7B Shadow drones.

Gen. Robert Neller, commandant of the Marine Corps, directed the units to conduct an “operational reset,” a 24-hour period without flights, at some time within the next two weeks. Spreading the pauses over two weeks will limit the number of aircraft that will be grounded at any one time during a time of great tension in several parts of the world, notably the Korean Peninsula.

In a brief statement, the Marines said each unit’s commander would decide when to suspend flight operations, timing the move to minimize disruption to operations.

Units deployed from their home bases can ask for an extension of the two-week time frame, said Capt. Ryan E. Alvis, a Marine Corps spokeswoman.

The Marines did not say what prompted the order. But it followed the crash of a Marine MV-22 Osprey on Aug. 5 in the Pacific Ocean off Australia that left three Marines missing and presumed dead; and the crash of a Marine KC-130T transport plane on July 10 in Mississippi, which killed 16 service members.

Hawaii had its own fatal Marine aviation crashes in recent years. On May 17, 2015, an Osprey crashed at Marine Corps Training Area Bellows while attempting to land in severe brownout conditions. Two California-­based Marines were killed. Eight months later, on Jan. 14, 2016, two big CH-53E Super Stallion helicopters collided at sea off Oahu during night training, killing all 12 on board.

Twelve MV-22s are based at Kaneohe Bay, with another 12 expected next fiscal year. The base also has AH-1W Super Cobra and UH-1Y Venom helicopters. An environmental report said 15 Super Cobras and 12 UH-1Y “Hueys” were slated for Kaneohe. A squadron of CH-53E Super Stallions also is based in Hawaii.

Additionally, the Marines have Shadow unmanned aerial vehicles and were scheduled to receive RQ-21A Blackjacks.

Details of how the III Marine Expeditionary Force in Okinawa, Japan, the higher headquarters for the Hawaii aircraft, will implement the operational pause were still being developed Friday, said spokesman Capt. Tim Irish.

The Marine Corps in the spring sent its largest aircraft element to date — four Ospreys, five Super Cobras and four Hueys, all from Hawaii — to Australia for training as part of the annual rotation down under.

During the reset, flying units will “study historical examples of completed investigations in order to bring awareness and best practices to the fleet,” the Corps’ statement said. That would not include the two recent accidents, which remain under investigation.

The different service branches occasionally call such pauses; the Marines said their last one was in August 2016.

In recent years the U.S. military has seen an increase in aviation accidents and a decline in the number of aircraft that are airworthy at any given time. Some members of Congress and military commanders have laid the blame on inadequate funding for maintenance and parts.

Making sure that a unit deployed abroad has the resources it needs “may leave its sister squadrons deficient in ready aircraft and parts as they attempt to train for their own upcoming deployments,” Gen. John Paxton, assistant commandant of the Marine Corps, testified before Congress last year.

Honolulu Star-Advertiser reporter William Cole and The New York Times contributed to this report.