BTW, Dduder --
They snuck in, not stormed.
They didn't exactly invade, they got delivered.
And with their training, especially the months spent drilling in the copy of Osama's mansion that was built for them, they could have been outnumbered five to one and pulled this off. Most terrorists barely have the equivalent of boot camp, which is like a college prep course -- SEALs have been to grad school.
The largest military academy of Pakistan was less than a mile away from Osama's bunker. And even though the U.S and Pakistan are allies, the Pakistani government did not give the U.S government permission to invade territory outside of where U.S troops are allowed to dwell. The Pakistani goverment was obviously shadowing Osama, meaning that those SEALs were potentially facing all the Pakistani army inside a hostile environment. You try to storm inside a bunker inside hostile terrain and then fight against heavily armed thugs that outnumber you. They did outnumber the SEALs. From some reports, there were 100 guards inside there. For casualties, there is no accurate figure but rumors have it to be between 5 to 35 guards killed.

