According to the movie's screenwriter.

The title of Disclosure Day tells you everything you need to know. In Steven Spielberg’s latest sci-fi blockbuster, there’s never any question of whether extraterrestrial life exists (it does) or whether we’ve made contact with it (we have).

Steven Spielberg's latest film, Disclosure Day, starring Emily Blunt and Josh O'Connor, is a sci-fi blockbuster with a surprise ending.

How David Levinson’s plan, Russell Casse’s sacrifice, and humanity’s unity defeat the alien invasion and secure a second chance for Earth.