While I feel it very unlikely that military force will result from this standoff, I have used the recent events in China as a reminder and wake-up call. A situation like this is the most fundamental, if unlikely reason for the right to bear arms. This was reinforced by a related thread at Glocktalk entitled "Are you a minuteman?", a thread about battle rifles.
Living here in California, I feel that if "bad things happened" California would be one of the main front lines. In addition, my location, in the Santa Clarita Valley, has some military significance. Santa Clarita, in addition to being close to Los Angeles and Edwards Air Force Base, is somewhat of a crossroads in California, where the east/west and north/south travel routes converge. While this was much more significant in the past before major highways, ask how fun it was right after the '94 Northridge quake, when the 5 and 14 freeways went down just south of Santa Clarita, and the roads jammed. I know that we were cut off such that doctors had to be flown in by helicopter. In fact, I have heard (I'm not sure if it is true) that a Chinese military strategist once named Saugus, CA (The main part of the SC Valley at the time)one of the top ten military strategic targets. This was obviously before freeways, but it would hold that by controlling this location, interstate ground movement, whether of people or supplies, would be severely hampered.
If faced with impending or occuring invasion by foreign military forces, I would resort to tactics mentioned by previous posters. My first response would not be to engage, but to escape and evade, only fighting if necessary.
In light of the fact that the enemy would have vastly superior firepower and numbers, I would try to muster at least a small group of trusted compatriots. I would utilize the sewer system, friendly american families, and the interconnected mountain ranges that surround this valley to conceal our actions.
At this time, I consider myself poorly prepared for an event of this magnitude. However, I do have a "go bag" that consists of an A.L.I.C.E. backpack, loaded with water, CB radio, a change of clothes, a sleeping bag, ammunition, maps of the area, both road and topo, and various other supplies. I am now saving for one of those Blackhawk Vests, which I will use to carry more ammo, accessories, and first aid equipment.
I have a Springfield M1A Scout, a rifle with good power, range and accuracy. I only have two ten round magazines, since I do not trust the junky 20 rounders that I have, so I am going to get several stripper clips, which I feel will be more compact, and I can afford dozens of them for every one magazine.
In addition, I hope to soon get a Mini-14 for closer range encounters. The unfortunate thing is that being in California, I cannot obtain an AR-15 or AK style weapon. Some would scoff at the Mini-14, saying to just stick with the M1A, but I feel that it offers some advantages.
First, the Mini is significantly lighter than the M1A. Second, the Mini uses a smaller cartridge, and therefore one can carry more ammunition for it. Third, magazines for the Mini are significantly less expensive than for the M1A (remember, I live in CA, and High-Cap mags are illegal to purchase, so I am limited to ten rounds.) Lastly, the Mini has less recoil than the M1A. This allows faster follow-up shots with multiple targets--a likely scenario wiht an invading army. In addition, the reduced recoil makes it a good gun to lend if I find others willing to participate.
I will stock enough ammunition, both .223 and .308, to be able to sustain, but still move around. Hopefully, I will be able to "plant" some ammo in a predetermined spot for aquisition later.
Besides the primary long-arms, I have a shotgun that I would use as a close range "fort-defense-weapon, and I woud carry either my Glock 23 or one of my 1911's, all of which are 100% reliable. Many people recommend a 9mm, due to high capacity and military compatibility, but I feel that since a handgun is sort of a "last ditch" weapon anyway, ammunition capacity is not so much an issue, and I could carry enough toget by. Besides, I would rather use the space to carry more rifle ammo. Also, i don't fully buy into the compatibility argument either. If I can gain access to ammunition, I can certainly gain access to those weapons. I would just take a Makarov or other weapon. If I can't use my weapons to obtain more, I won't be around too long anyway.
Hopefully it will never come to the point where I have to use this stuff, but if things happen, I will fight to protect my country, my family, and myself.