The Lawrence Livermore National Laboratory in California is transitioning to minimum-safe operations in response to the COVID-19 pandemic, a move that by next Monday will sharply shrink staffing levels and curtail some scientific activity at the Department of Energy nuclear weapons facility.

Livermore Director William Goldstein made the announcement Monday night after the government of Alameda County, which includes the lab, announced a shelter-in-place order for citizens. Other San Francisco Bay-area counties issued similar directives, essentially closing all businesses in an effort to prevent people from transmitting COVID-19 to one another.

“During Minimum Safe Operations, the Laboratory will reduce on-site staffing to a minimum number necessary to ensure the safety and security of the site and its facilities, as well as to carry out a very limited number of mission-critical activities,” Goldstein said in a statement posted on Livermore’s website. “All other on-site activities will be temporarily halted. This transition is expected to take several days, with Minimum Safe Operations fully in place by Monday, March 23.”

Goldstein said staff able to telework should begin doing so on Tuesday. The lab has about 6,300 employees.

Livermore is leading the National Nuclear Security Administration’s (NNSA) program to modernize nuclear warheads intended for future air-launched cruise missiles and silo-based intercontinental ballistic missiles. Those warheads, the W80-4 and W87-1, respectively, will head into the NNSA production pipeline later this decade, when the nuclear enterprise finishes work on the B61-12 gravity bomb and the W88 Alt-370 submarine-launched ballistic-missile warhead led by the Los Alamos National Laboratory in New Mexico.

Aside from the warheads themselves, Livermore is critical to the effort to restart production of war-usable plutonium pits at Los Alamos by 2024. The first run of pits will be for Livermore’s W87-1 warhead.

COVID-19, caused by the novel coronavirus that broke out in China last year, is rapidly disrupting American life. Restaurants, businesses, professional sports leagues, and even the nuclear security enterprise are all reeling from the effects. Confirmed U.S. cases, which do not take into account asymptomatic individual who can transmit the disease, have risen by a factor of nearly 20 inside three weeks. More than 3,400 cases have been confirmed, along with 68 deaths.

The Sandia National Laboratories is among the U.S. institutions making telework mandatory for employees who are able.

“As of Monday, March 16, Sandia is urging all employees who can work from home to do so until further notice,” a spokesperson for the Albuquerque, N.M.-based lab wrote Monday in an email. About 4,200 Sandia employees are working remotely during this stage of the pandemic, representing roughly one-third of the labs’ nationwide workforce of 14,000.

A spokesperson for the Los Alamos National Laboratory did not immediately reply to a request for comment late Monday evening. A recording on Los Alamos’ Lab Update Hotline said the site “is on a regular operating schedule.” The message did not mention COVID-19.

Meanwhile, the broader Department of Energy will soon “deploy a strategic plan to ensure operational effectiveness of the Department while maximizing telework opportunities for the workforce … including our Washington Headquarters, National Laboratories and sites around the country,” a spokesperson for Secretary of Energy Dan Brouillette wrote Monday in an email.