Marines check their weapons during a call-away drill in the hangar bay of the forward-deployed amphibious assault ship USS Essex.

WASHINGTON — A Pentagon official said Tuesday that the number of coronavirus cases within the military and the overall Defense Department is probably higher than the total that has been reported.

"I think that it is likely that the number is higher," U.S. Air Force Brigadier General Paul Friedrichs, the senior health official for the Joint Chiefs of Staff, said during a press briefing. He added that currently there are six known cases of COVID-19: three active-duty service members, one civil servant, four dependents and one contractor.

"I think it is likely given what we are seeing around the world and the fact that we have people all over the world that there are more than nine people affiliated with the Department of Defense," he explained.

Friedrichs added that the DOD currently has 13 laboratories carrying out tests on the coronavirus.

The virus — which has already killed more than 4,200 people and infected at least 118,096 people around the world — is spreading from the U.S. Indo-Pacific Command, the largest of all geographic combatant commands.

On Monday, Army Secretary Ryan McCarthy said in a statement that the top U.S. Army commander in Europe may have been exposed to the coronavirus.

A spokesperson for U.S. Army Europe told CNBC that Army Lt. Gen. Christopher Cavoli's possible exposure took place during a conference with land force commanders on Friday in Wiesbaden, Germany.

Last week, the nation's highest-ranking military officer said the coronavirus posed a limited risk to U.S. service members.

"Right now the overall broad impact to the uniformed U.S. military is very, very minimal. It's not to say that it's zero, but it's very minimal, very few cases diagnosed, etc.," U.S. Army Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said during a March 2 Pentagon briefing.

"That's not surprising because we have a young demographic, healthy demographic, lots of immunizations, so on and so forth," he said, adding that the department has postponed joint military exercises on the Korean peninsula.

Milley also added that the coronavirus had not yet impacted the military's global supply chain.

Defense Secretary Mark Esper is expected to approve additional measures to better safeguard those in the Pentagon, one of the world's largest office buildings, where more than 20,000 people work every day.