By the time the aircraft carrier Theodore Roosevelt was ordered to port in Guam on March 26, the hulking ship was already being ambushed by the outbreak of an invisible enemy.

At sea on March 24, the first three cases were reported. Within 24 hours, the number of infected more than doubled. Each subsequent day yielded more confirmed cases, numbering 615 as of Wednesday. A 41-year-old chief petty officer became the first to succumb to COVID-19 on Monday, four days after being found unresponsive by other quarantined sailors.

Officials retracing the ship’s activity pointed to a scheduled port stop in Da Nang, Vietnam, as the source of the outbreak. The oft-questioned decision to continue with the long-planned 25th anniversary celebration of U.S. and Vietnamese diplomatic relations was made at a time when the country had only 16 confirmed cases, all of which were reportedly confined to the northern city of Hanoi, Chief of Naval Operations Adm. Michael Gilday said.

As Navy officials analyzed the ship’s chronological movement, however, the once-firm belief of where the virus first meandered onto the ship was called into question — and potentially debunked.

According to a Wall Street Journal report Wednesday, Navy officials now believe the outbreak on the carrier Roosevelt was initiated by the ship’s routine flight operations.

Numerous carrier on-board delivery flights originating in Japan, the Philippines, and Vietnam occurred in the days following the ship’s departure from Da Nang, the report said. With some of the first Roosevelt sailors to contract the virus coming from the carrier’s air wing, the picture began to clarify.

Furthermore, the eight sailors who first tested positive did so over the course of March 24 and 25, more than two weeks after the ship departed Da Nang — a time period in excess of the virus’ incubation. A Navy Times request for officials to confirm which units the first infected sailors belonged to was not returned as of publication.

Additional evidence materialized when the Navy pinpointed a hotel in Da Nang, where 30 sailors had stayed while Roosevelt was in port. Two British nationals who stayed at the same hotel later tested positive for COVID-19, the WSJ reported.

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Each of the 30 sailors who were at the hotel, however, yielded negative test results.

Still, Navy officials are holding off on saying for certain where the virus onboard Theodore Roosevelt originated.

“We just don’t know,” one official told the Wall Street Journal.

Uncertainty has loomed over the Big Stick in the weeks since the first COVID-19 cases emerged.

Upon arriving pierside in Guam, former Theodore Roosevelt commanding officer, Capt. Brett Crozier, penned a letter pleading for Pentagon assistance to evacuate the majority of his sailors off of the ship and into isolated quarantine.

“We are not at war. Sailors do not need to die,” he wrote. “If we do not act now, we are failing to properly take care of our most trusted asset — our Sailors.”

Crozier was subsequently fired by former Acting Secretary of the Navy Thomas Modly after the captain’s letter was leaked to the San Francisco Chronicle.

Days after leaving the ship to rousing applause and chants of his name, Capt. Crozier tested positive for COVID-19. Like many of the sailors he used to command, Crozier is now in isolated quarantine.

Modly then flew to Guam to offer Roosevelt sailors an explanation for their captain’s hasty dismissal, a last-minute tirade that, according to estimates obtained by the Washington Post, came with an airfare tab of $243,151.65.

“It was a betrayal," Modly told Roosevelt sailors over the ship’s 1MC intercom.

“And I can tell you one other thing: because he did that he put it in the public’s forum and it is now a big controversy in Washington, D.C. If he didn’t think, in my opinion, that this information wasn’t going to get out to the public, in this day and information age that we live in, then he was either A, too naïve or too stupid to be a commanding officer of a ship like this. The alternative is that he did this on purpose.”

According to a USA Today report Tuesday, Modly expensed the trip before formally submitting a waiver to side-step a policy that limits “senior officials to one air crew per trip to curb the cost of travel by military aircraft,” the report said. The former Navy secretary took the trip while only informing the “Pentagon orally that he intended to use more than one crew.”

Pressured by lawmakers on Capitol Hill following his infamous speech — the audio was obtained by Military Times — Modly resigned.

Now, in the aftermath of his ill-advised trip and potential exposure to COVID-19, Modly, too, is in quarantine.

Since Crozier’s firing, approximately 85 percent of Roosevelt’s crew has been evacuated from the carrier, Navy officials said.

In addition to the sailor who died from coronavirus complications, five sailors have been hospitalized. One of the five crew members has been moved to the ICU.