You may have heard that President Trump signed an executive order Friday, March 27 allowing the military to recall members of the selected reserve and some former service members to active duty in support of the government's response to the novel coronavirus (COVID-19) outbreak.
While this sounds ominous, the executive order is mainly a formality giving the Pentagon the authority to recall reserve members as necessary. A federal law (10 U.S. Code § 12302) that has been around since 1953 authorizes the president to recall up to one million reservists for up to two years in times of national emergency.
The military branches have also started to gauge interest from recently separated members on volunteering to return to active duty in response to the COVID-19 pandemic. The Army, for example, recently contacted 800,000 retired members asking about their willingness to return to active duty and help the service fight the pandemic. More than 17,000 retirees, representing various specialties, have responded at the time of this writing.
https://www.military.com/daily-news/2020/03/30/trumps-irr-recall-order-what-you-need-know.html