Service members, civilian employees and visitors, regardless of vaccination status, are now required to wear masks indoors on DoD installations and facilities in areas with “substantial or high community transmission” of COVID-19.

The new and stricter rules issued by Deputy Defense Secretary Kathleen Hicks were announced July 28 after the Centers for Disease Control and Prevention updated its guidelines as the U.S. grapples with rising COVID-19 cases. The revision comes just one month after DoD said fully vaccinated service members and civilian employees no longer had to mask up on military installations.

The mask requirement “applies to all service members, federal personnel, contractors, and visitors when indoors at all properties owned by the Department in those areas, in accordance with updated CDC guidelines,” Deputy Pentagon Press Secretary Jamal Brown said in a statement.

Personnel who are not fully vaccinated must also continue to practice social distancing according to DoD and CDC guidelines, Hicks said in the memo.

In a separate memo, also issued July 28, Michael Donley, the Pentagon’s director of administration and management, is requiring masks indoors for all service members, employees and visitors on the Pentagon reservation.

After a sharp decline, the number of COVID-19 cases across the country began to increase in mid-June—rising by about 300% between June 19 and July 23—because of the highly transmissible delta variant of the virus and a decline in vaccinations, according to the CDC.

The guidance for masks in indoor public places applies in parts of the U.S. with at least 50 new cases per 100,000 people in the last week, the Associated Press reported. That includes 60% of U.S. counties, officials said.

Those areas, according to the CDC, have “substantial” community transmission. Areas with more than 100 new cases per 100,000 people in the last week are in the “high” transmission category.

More information on the CDC guidelines can be found here. Check the status of your community here.

Hicks’ memo can be found here.