Soundtrack composed by Frank Klepacki
If you're a Frank Klepacki fan you'll surely know where this track gets its inspiration from. If you think it sounds a bit similar to Command & Conquer's iconic "Act on Instinct", you'd be right. Considering "Act on Instinct" is one of my favourite tracks from C&C, it's no surprise that "Act on Invasion" is one of my favourites from the Universe at War soundtrack. It even has similar passages to the original.
"Act on Instinct" is often remixed and covered and was even redone for the C&C Remastered Collection.
The soundtrack was originally offered for free off the Petroglyph forums but you can download a copy from the Free VGM section at Choicest Games. It's also available for streaming off Frank Klepacki's website.