love the movie but a little confused

Rating: 10/10 (22 March 2020)

Ok I own all the Transformers movies and I love to rewatch then a lot but I am still confused about the scene in Chicago when Sentinel Prime calls for the city blocked so that nobody can get in. Where in the blue blazes did all of those Alien ships come from that start attacking the city and the people? Nobody ever mentions where those ships come from or how they are associated with the Decepticons