Cases of coronavirus quickly multiplied aboard the aircraft carrier USS Theodore Roosevelt on Thursday as 15 more sailors were found to have been infected, prompting tests for all 5,000 crewmen onboard, according to officials from the US Navy.

The Navy first announced on Tuesday that three sailors tested positive and were airlifted to a Pacific hospital. On Wednesday 5 more sailors were diagnosed. When the ship docked for a scheduled stop in Guam by Thursday, the number had risen to 23 sailors, according to a Defense official who was not allowed to speak publicly.

"We are doing our utmost to isolate those who had contact with other sailors and avoid further infection," the Navy said.

While at sea the sailors became ill, raising concerns about the further spread of the highly infectious disease and the resulting pandemic strain on military readiness.

The Pentagon has already cancelled or curtailed major exercises in war-training, quarantined thousands of soldiers, closed recruitment centers and imposed international and domestic travel restrictions.

There are currently 800 COVID-19 test kits on board but more are being added. Aboard the carrier there are about 5,000 sailors who will need to be checked. Symptomatic sailors, individuals who have come into contact with contaminated persons and vital watch standers should be the first priority, Navy officials said.

According to Admiral Michael Gilday, chief of naval operations, they expect further positive tests, and those sailors who test positive will be transferred as required to the U.S. Naval Hospital Guam for further assessment and care. "Simple access for Roosevelt's sailors during the port visit will be limited to the pier. No base or regional personnel can access the pier," Gilday said.

Defense Secretary Mark Esper admitted Tuesday that the coronavirus has impaired readiness, the phrase the military uses to gauge its combat ability. Since the pandemic swept across the globe many major training operations have been canceled. The Pentagon continues to be able to counter any challenges, he said.

The USS Theodore Roosevelt, dubbed the "Big Stick," is currently in Guam where a visit to the port was originally planned. While in port, mariners will not be able to leave the pier area, and the pier will not be reached by base and regional staff.

Across the US military, officials raced to contain the virus before it could do more harm through the ranks and restricts the capacity of the Pentagon to meet adversaries' challenges.

Cases of COVID-19 continued to increase Wednesday, hitting 574 cases among soldiers, their families and civilian workers, said the Pentagon. That's a 38 percent rise compared to 415 on Tuesday.