Thursday is a test run for our DOD and NSA
The football is the black briefcase that follows all Presidents. The test on Thursday will allow our NSA and DOD to see if there is any interference.
If there is they will be able to know where its coming from, what form is being used etc.
https://nsarchive.gwu.edu/briefing-book/nuclear-vault/2018-07-09/presidential-control-nuclear-weapons-football
It is not clear when or why the “Black Bag” became known as the Football[2], but during the Eisenhower administration it became the practice, when the president was traveling, for a military aide to carry a briefcase including emergency action documents