On Friday, Navy leaders announced that they would not reinstate Captain Brett Crozier. On March 30, Captain Crozier was removed from command of the USS Roosevelt after his plea to evacuate the aircraft carrier’s sailors in Guam, so they could be treated for COVID 19, became public. Chief of Naval Operations Admiral Mike Gilday criticized Captain Crozier for his lack of planning, despite considerable evidence that Captain Crozier pushed Navy commanders for a swift evacuation.

The investigation shed little light on what led to the crisis, specifically the decision to proceed with a March 5 “port call” in Vietnam. While in Port Da Nang, an estimated 4,500 sailors disembarked to meet with “the people of Vietnam through tours, professional exchanges, and community relations events” – activities that could spread the virus. Of course, it’s impossible to be certain that the Roosevelt’s port call led to the spread of the virus onboard the ship, but Gilday conceded the port visit was the most “likely” source of the virus’s spread.

Despite this, Gilday defended the port visit and said none of the officers responsible for that decision would face reprimand. Why did the Navy decide to go ahead with the port call in Vietnam, which had confirmed the presence of coronavirus, and who is responsible for that decision? Here’s what we know:

1. A Vietnam “presence mission” trumped pandemic concerns

The U.S. government considers port calls essential to the U.S. Navy’s “presence missions.” By visibly deploying U.S. navy ships to foreign ports and Freedom of Navigation Operations, the government hopes to signal a strong commitment to a “free and open Pacific.”

Both the Department of Defense and State Department saw the Roosevelt’s port call in Da Nang as a strategic way to strengthen its relationship with Vietnam, at a time when U.S. influence in the Philippines might be in decline. And China’s recent military activity has increased in the Spratly Islands – territory claimed by both China and Vietnam. For the Navy, the port call signaled the importance of the Navy’s carrier fleet in maintaining U.S. influence in Asia, at a moment when U.S. budget support for ships is in decline.

But military analysts and political scientists also consider port calls “cheap talk,” a symbolic use of force. There is little evidence that U.S. “presence missions” are effective deterrents against aggression, or serve as meaningful signals of resolve. And whatever deterrent value was gained from the March stop in Da Nang, much more might be lost in “military readiness” from the spread of the virus.

2. Even during a pandemic, there were pressures to conduct “business as usual”

If the port call brought limited strategic gains, why did leaders go forward? Three reasons likely explain the decision to disembark at Da Nang.

First, when faced with uncertainty, militaries tend to adhere to standard operating procedures, the rules already in place to guide operations. The Roosevelt’s port call was timed to commemorate the 25th anniversary of the normalization of diplomatic relations between the United States and Vietnam. Planning involved the Pentagon and the State Department. Leaders would be loath to depart from these complex operations.

Second, leaders likely worried that cancelling the port call could damage relations with Vietnam. Approval for the aircraft carrier’s visit required a consensus among Vietnam’s 19-member Politburo. Vietnamese officials had reported that there were only 16 coronavirus cases in the country, all well north of the port. Keeping the port call on the roster signaled U.S. officials’ trust in their Vietnamese counterparts.

Cancelling the port call would also be an economic loss for Vietnam – and cause potential damage to the bilateral relationship. Port calls often bring in millions of dollars to the host country, as sailors disembark and support the local economy.

A third factor may have been morale on the Roosevelt. Port visits – perhaps once a month – are one of the few bright spots for sailors deployed at sea for eight or nine months. Seven days a week, sailors work 8 to 10-hour shifts fixing engines and computers, tracking aircraft and ships, or making meals. After about 30 days at sea, an aircraft carrier will pull into port for four days. Of those four days, a sailor is free for three. The loss of a port visit and another 30 days at sea without respite can be tough on a ship’s crewmembers.

3. This was U.S.-Indo Pacific Command’s decision – not Captain Crozier’s

While President Trump criticized Captain Crozier for going ahead with the port call, that’s a decision outside of the scope of an aircraft commander’s authority. As the USS Roosevelt’s commander, Captain Crozier was responsible for the internal functions of the aircraft carrier. His task was to oversee the operations of the ship and be accountable for the performance of both ship and crew.

Authority to cancel the port call lay with U.S Indo-Pacific Command, in consultation with the departments of Defense and State – who helped coordinate the visit. The commander of Indo-Pacific Command, Admiral Phil Davidson, decides where naval assets are deployed. If there was information that a port call would threaten the crew of an aircraft carrier, Indo-Pacific Command had the authority to either keep sailors on the ship when it docked or cancel the port call entirely.

The coronavirus timeline suggests Indo-Pacific Command had both the time and the information needed to change course. At the end of January, shortly after the Roosevelt left its San Diego home port, the World Health Organization declared a global public health emergency. On Feb. 14, well before the carrier arrived in Vietnam, the Navy ordered all ships in the Indo-Pacific region that had made port calls to quarantine at sea for at least 14 days.

The USS Roosevelt crisis comes on the heels of several events that raise concerns about leadership command in the Pacific. The Fat Leonard scandal, for instance, uncovered systemic corruption within the Pacific Fleet. Investigations last year into two separate collisions in 2017 – the USS John S. McCain and the USS Fitzgerald – revealed that commanders had failed to train and equip surface combatants properly, as the Navy attempted to maintain an unsustainable operations tempo.

All of this suggests that the March 2020 port call in Vietnam was a symptom of a more dangerous ailment. When the Navy finishes its coronavirus fight, it faces a raft of decision-making dysfunctions beyond this current pandemic.

This post was originally published on April 10, and was updated on June 19.

Stacie Goddard is professor of political science at Wellesley College and a non-resident fellow of the Quincy Institute. She is the author of When Right Makes Might: Rising Powers and World Order (Cornell University Press, 2018).

Captain William Cameron is a retired naval officer who served most of his career in the Pacific and served as Director of Operations in the White House Military Office during 9/11.

Pierce MacConaghy is a law student at the University of Virginia and former naval intelligence officer who served aboard an aircraft carrier and as a member of the Chief of Naval Operations and Secretary of the Navy’s briefing staff.