Fewer than half as many U.S. Marines than originally planned will rotate to Australia’s Northern Territory for a training mission this summer that was cut short by the coronavirus, according to the Australian Minister of Defence.

The Marine Corps on May 5 announced the resumption of the rotation to the northern Australian city of Darwin. It had been scheduled to begin in March but was delayed following an order that month from Defense Secretary Mark Esper barring nearly all official movement overseas for Defense Department personnel.

“The modified rotation will involve around 1,200 Marines who will exercise exclusively at Defence training areas in the Northern Territory until September,” the Australian Ministry of Defence said in a statement Thursday.

Fifty-four Marines who arrived in Darwin in an advance party in March have already gone through a 14-day quarantine and begun training with their Australian counterparts.

The first group of additional Marines will disembark at Royal Australian Air Force Base Darwin in early June, beginning the Australian component of a detailed quarantine and testing regime, the Australian statement said. “They will then be screened and tested for COVID-19 upon arrival in Australia, before being quarantined for 14 days at specially prepared Defence facilities in the Darwin area,” the statement said.