In response to suggestions by a lunatic in the US Oval Office, Green Party Canada’s leader Elizabeth May suggested Canada should invite western states Washington, Oregon and California join B.C and split from Canada to form the ‘Cascadia’ eco-state.
(Note this article is from Jan 8, 2025 and Elizabeth May has since become co-leader of the party alongside Jonathan Pedneault).
I would point you to the siege of Hostomel airport in the Ruso-Ukrainian conflict. It is ridiculously easy to render an airport unusable, temporarily if you think you can hold it, and semi-permanently if you’re less confident.