I doubt the general public would approve of a budget for buying thousands and thousands of AMD video cards. I'm not so sure that would get past any budget hearing.
I'm sure the government has enough computers that they could pull a big enough hash rate to seriously cripple the system if the wanted.
i rather doubt it. you'd need several Jaguars to even make a dent in things.
Pffft... Jaguars are supercomputer
With 15 millions $ it is possible to have more than 51% of the network hashrate.
It doesn't even require the general public to approve the budget and blablabla, 15 millions are nothing for the government (or for the banks)