As an example, in a recent game I had the science victory locked up. Catherine and Hiawatha were both building parts but had gone Order so they had to hard build them while I went Freedom and was just buying them as I teched into the tree (this seems very cheater, by the way - I wish NASA just "insta-bought" the space shuttle or ISS parts).
After I purchased the last part (the engine, I think?) I parked it in my capital and sent a spy to Catherine to inform her of my progress. After shmoozing around Moscow and getting me a good view of her capital, I politely informed her of my intent to cause mischief, declared war and paradropped 12 XCOM units into the tiles around her capital from my Barracks/Armory/Military Academy military industrial complex city. She was shocked and horrified and probably a little disappointed, but I assured her we would we be BFFs on Alpha Centauri as I set Moscow to the torch and clambered onto my spaceship.
It gave me a great deal of satisfaction.