If you're being targeted by a nation state you will face all sorts of things to deal with that can't be handled by buying a Thinkpad with cash from a randomly chosen used computer store. Like bugging your residence and office, bugging your car, putting advanced GPS tracking devices on your car, rubber hose cryptography, hardware keystroke loggers inserted in your equipment while you're known to be away from your home or office, full disk copies of your laptop/desktop being taken (clonezille-type) by breaking into your office while you're away, all sorts of shit.