This is actually starting to make me a little nervous.
NATO could invoke Article 4 after Russian missiles struck Poland
Top U.S. lawmaker warned on Tuesday of significant consequences for Russia — including a Western military response — if it’s determined that Moscow was at fault for a deadly airstrike in Poland.
Russia claims it was a false flag.
Update:
Looks like it was Ukrainian air defense missile, so we can relax a little, but I think it shows how fast things can go in a wrong (really bad) direction.