UPDATED: 1:55 p.m. ET.

Lockheed Martin has paused production of F-35 Joint Strike Fighter aircraft at a Mitsubishi Heavy Industries Japan factory because of the coronavirus outbreak, a top Pentagon official said Wednesday.

Some employees at an Italian F-35 factory, owned by Leonardo, have been told to work from home, Ellen Lord, the defense undersecretary for acquisition and sustainment, told reporters after speaking at a McAleese and Associates conference in Washington.

It’s the first sign that weapons manufacturing is being disrupted by the global outbreak of COVID-19, which has shuttered factories across Asia.

“I believe they have decided to shut down for a week,” Lord said of the Japanese factory. “Right now, it doesn’t look like it is affecting deliveries" of the jet, she said.

Lt. Col. Mike Andrews, a spokesman to Lord, wrote in an email later Wednesday morning: “In Japan, to comply with Japanese Coronavirus directives Mitsubishi Heavy Industries is temporarily closing the Japanese [final checkout and assembly facility] for 1 week.”

Only Japanese aircraft are produced in Japan.

Andrews also confirmed that Lockheed has restricted travel to the Leonardo factory in Cameri, Italy. Pratt & Whitney employees at that site have been told to work from home. Pratt builds the F-35 engine, he said.

But production is continuing, Andrews wrote: “There have been no impacts to the production line.”

Beyond the F-35, Lord said weapons programs with global supply chains are not being affected by the coronavirus outbreak.

“Right now we have not seen any effects, but I have a team working on that very heavily right now,” Lord said.

Lockheed builds most F-35s in Fort Worth, Texas, but some allies' jets are assembled in Japan and Italy.

“F-35 production in Fort Worth, where the majority of F-35 aircraft are produced, remains unaffected at this time by the coronavirus,” Brett Ashworth, a Lockheed spokesman, said in a Wednesday afternoon email. “We are working with our customers and partners to mitigate any impacts to F-35 international [assembly factories] operations in Italy and Japan.

“The health and safety of our employees remains our top priority,” he said. “We advised employees to avoid travel to, through and from northern Italy in alignment with U.S. State Department guidance.”

The 500th F-35 was delivered on Monday, Lt. Gen. Eric Fick, the head of the F-35 program, said during a speech at the McAleese conference. That aircraft went to the Vermont Air National Guard.