Sparks has recently posted about Internet service interruptions, some of which are the result of intentional action. See this post, too (and my readers may recognize the picture of the FT-817).
Today, I ran across this story on Ars Technica, reporting a fiber optic cut near San Francisco which was the twelfth such interruption in that area this year.
A sufficiently motivated party could cut several such fiber optic lines, or take out a colo facility in which many such lines pass through, and thereby cut off comms for a large number of people for a significant period. Given our current dependence on the Internet and telecommunications, this could be disastrous for those affected.
BTW, from the viewpoint of someone who's worked for an ISP for nearly 15 years, if somebody takes out a colo facility, Shit Just Got Real.
The Internet was designed to route around breaks but as it has grown in the past 15 years, the level of overall redundancy has dropped in many areas. Too many parts of the infrastructure are vulnerable to intentional disruption. With Islamic terrorism happening more frequently on US soil, I am concerned that at some point they'll go for infrastructure.
This is why I highly recommend getting at least a General Class amateur radio license. The General Class license gives you operating privileges on most of the frequencies allocated to ham radio operators in the US, and isn't much more difficult to get than the entry level Technician license, now that there is no Morse Code requirement.
There's a lot of overlap in the Tech and General exams, but you get a lot more privileges on High Frequency (HF) with the General ticket. HF is what's needed for long distance communications, or certain kinds of regional comms (see, NVIS).
The ARRL maintains a web page with info on getting licensed, including training and finding an exam, here.
You need to get licensed now, before you need comms, because you need to know how to operate your radio, and understand on-the-air procedure. You cannot expect to be able to turn on a ham radio, press a button, and talk to someone like you're using walkie talkies. Just like having an AR-15 doesn't make you a Navy SEAL, having a radio doesn't make you a competent operator. It takes practice, and the only way to get it is to get on the air.
If you're not licensed, don't expect to be able to get on the air with a fake call sign. Not only will licensed hams not talk to you, they may very well track you down and sick the FCC on you. The penalties for unauthorized transmissions can include $10,000 fines.
It's not a bad idea to have unlicensed communications options available, as well. FRS and GMRS* are good for local comms, as is CB Radio. See Dialtone's posts on the "Jungle Telegraph," here and here.
* I know, GMRS requires a license. However, I'll bet that 90% or more of bubble pack FRS/GMRS radios are operated without one.