The defense industrial base is considered part of the United States’ critical infrastructure by the Department of Homeland Security, and as such has a “special responsibility” to maintain normal work schedules amid the COVID-19 coronavirus pandemic, according to a memo written March 20 by the Pentagon’s top weapons buyer.

In the memo, Undersecretary of Defense for Acquisition and Sustainment Ellen Lord told contractors to follow guidance issued by the Centers for Disease Control and Prevention and from state and local authorities as related to the widespread coronavirus, but maintained that workers who help develop U.S. national security products and services are required to stay on the job. The memo was first reported Friday by Bloomberg News.

Lord includes a copy of a March 19 memo issued by Christopher Krebs, the director for the Cybersecurity and Infrastructure Security Agency (CISA) within DHS in her notice, which went out to defense industry associations, governor associations and lawmakers on Capitol Hill. That memo includes a list of workers who are considered essential across the U.S. government, from law enforcement, to public works, to energy and food and agriculture.

For the defense industrial base, those critical workers are in sectors including but not limited to: aerospace; mechanical and software engineers, manufacturing/production workers; IT support; security staff; security personnel; intelligence support; aircraft and weapon system mechanics and maintainers. Companies across the country and the globe are encouraging their employees to telework as much as possible over the next few weeks in order to limit the virus’ spread.

The CISA memo also highlights “personnel working for companies, and their subcontractors, who perform under contract to the Department of Defense providing materials and services to the Department of Defense, and government-owned/contractor operated and government-owned/government-operated facilities.”

In her memo, Lord noted: “We need your support and dedication in these trying times to ensure the security of our Nation. I understand that this national emergency presents a challenge and we are dedicated to working closely with you to ensure the safety of the workforce and accomplishments of the national security mission.”

Lord met with Sen. Jim Inhofe (R-Okla), the Senate Armed Services Committee chairman, earlier on Friday to discuss the memo and “other department COVID efforts with industry,” said Air Force Lt. Col. Mike Andrews, Pentagon spokesman in a Friday email. “She remains committed to daily communication and collaboration with the defense industrial base, especially the defense industry trade associations. In addition, she’ll be contacting several state Governors to discuss state-specific critical infrastructure and essential workforce efforts.”

Several Pentagon officials have been engaged in daily discussions with Hill, industry and state leaders to address a variety of issues related to COVID-19. The officials include Assistant Secretary of Defense Kevin Fahey, Deputy Assistant Secretary of Defense for Industrial Policy Jennifer Santos and Defense Pricing and Cost Director Kim Herrington. Industry associations involved include the Aerospace Industries Association, National Defense Industrial Association, Professional Services Council, National Association of Manufacturers, and Chamber of Commerce.