Granted, the tone of SG1/SGA was a little more gung-ho, but Cheyenne Mountain has stood up to the likes of the System Lords and Anubis. Yes, I know the Asgard were watching our butt at the time. It still seems really weird that they're now so completely vulnerable to what's essentially the Space Yakuza.
Cloaked cargo ship, naquadriah bomb...fine, sure. I'll accept that they're somehow able to source naquadriah (something that, presumably, only occurred "naturally" on Jonas' homeworld and only a handful of people in the galaxy know how to synthesize). I'll accept that, after all this time, they havent figured out a way to break a cargo ship's cloak (with the Asgard database now, no less), even though for years they've been talking about cloaked cargo ships as a potential weapons delivery device.
But come on, the amount of infiltration in the SGC, really? Case in point, how do you get one of your own guys in uniform on the base? Dont they check ID badges when you come in, dont they check against the duty schedule to see if you exist? Wouldnt you eventually trigger some shibboleth to the other airman that, you know, you're not from Earth and you dont know what a McDonalds is?
It just seems like it should take a lot more than one pilot with a crude bomb and a cloaked ship to take out SGC. If it was that easy, you gotta believe someone else woulda tried it by now
I know they cant just keep coming up with bigger and badder enemies, from Goa'uld to Anubis to Ori. I just think they havent really done a good job of establishing the LA as a credible menace, they've only really done a good job of making the SGC seem like they're slacking off and letting their guard down.