Complete conjecture, how about this:
Alaska's pork runs out because of excesses like the 'bridge to nowhere' amid a growing wave of resentment at how much federal money is being spent per citizen compared to other states. Alaska chats amongst itself and realizes that the natural resources it controls make it a potentially very powerful figure. That, plus the growing divide between our nanny state government and what the founding fathers envisioned.
It secedes and becomes the Alaskan Republic. It initially offers to allow the existing military bases to stay, subject to a reasonable lease. The US government declines, spinning it to look like the "rogue alaskans" kicked them out.
Florid faced congressmen hold endless hearings denouncing the "theft of rightfully owned resources" that "are the rightful legacy of the american people" and pressures Canada to impose trade sanctions while simultaneously levying a VAT of some sort on good exported to Alaska from the US.
The Alaskan Republic begins trading heavilly with the Japanese and Chinese, the petroleum and timber growing more and more valuable.
Meanwhile, the US government is under increasing pressure. The sudden loss of the petroleum reserves and the cessation of trade is showing up in the economy. Government military planners begin to look north with envious eyes....
