Is it possible we areforgetting the most obvious. Not china or india, the one political and economic bloc with the industrial strength, population base and military knowledge and history. The european union.
Obviously not at the moment, but in twenty years time. The EU will have moved up to the borders of Russia, possibly including Russia, it will have some kind of close status with with Turkey, it may include Israel. The northern african states will have some kind of associate status ( morocco actually applied to join in the 1980s, it was rejected, because it wasn't in the EU, but that resulted in special status for the north african countries.
effectively a modern industrial state of close to 800 million people with borders stretching from the pacific to the atlantic and economic strength and ties stretching deep into africa, the middle east and central asia.
why would it attack the USA. well what if we don't make the breakthrough in new energy sources. The EU and the USA jockeying for influence over the oil rich states of the middle east or the vast mineral resources of antartica.
Imperial overstretch could do for the USA what it has done for every empire( for the US is an empire, just a land empire, in my opinion) . The cost of enforcing its will across the known world. Will a combination of the war on terror and the financial crisis do what world war 1 did to the british empire, bankrupt it?
Here is one scenario
A civil disaster or bloodbath in south east europe, maybe the algerian civil war starts up. The europeans discover they have no military depth, and the US has to step in and solve the problem. perhaps india and pakistan have major conflict and the EU discovers it hasn't got the ability to send help.
It starts to retask and re arm, instead of having 25 small armed forces it has integrated armed forces. It may build aircraft carriers, more than just the possible 3 of france and the UK. It has the best of german engineering, quality british and french and german military soldiering ( no cracks about the french please), and the sheer weight of numbers of young men from places like turkey looking for military employment. That is ignoring Russian soldiering and Israeli ingenuity( if they join)
If countries from the middle east join the EU, that could produce a huge supply of underemployed young men who need jobs.
back to the scenario
as the US is overextended, financially and militarily, it cuts defence spending, which is still greater than the next 10 countries combined, whilst the EU finally enacts its plan for military integration.
( I think there was british tv drama about future EU/ US war over resources, a couple of years ago)
the next generation of weapons is developed. Star wars finally works, meaning nuclear holocausts aren't credible. new ships, new planes, electronic warfare, maybe EMP weapons ( i think i read something about very early planning for them)
relations are sharp between the EU and the USA, over resources, political views -whatever. The EU has developed its new aircraft carriers to project its power, once again the US is not the only superpower. The EU believes its only a matter of time before war and decides to strike first
the EU sends an armada to the south atlantic as a dummy, the US sends a fleet to shadow and observe, whilst the major fleet readies in across EU ports.
the first day, EU special forces, launch attacks across USA, at pearl harbour, at major naval and airforce installations, in space. cruise missiile strikes at targets across the US.
by the end of the first day, several US carriers have been sunk by EU submarines.
A large invasion force sails across the atlantic.
the special forces have been successful in partially cripplying the ability of USAF to ready large numbers of planes.
The EU invasion force lands... in canada, the canadians are brushed aside ( sorry but your army is 22,000 strong, the last time I read numbers)
the US army rushes to meet the invasion.
The EU drops several divisions of parahute troops into jacksonville as part of its attempt to form a bridgehead. ( yes I know its a little far fetched, but hey)
suddenly the US is facing an army from canda and heavily armed light infantry(I am thinking something on the lines of the british parachute regiment, someone described them to me as the kind of soldiers you throw into a battle to beat the hell out of your enemy, very very aggressive). it has to direct two separate attacks.
the EU has aircraft carriers against a vastly reduced numbers of planes which are on home soil. Very large air battles.
EU armoured divisions rush into new york state as US armoured forces rush up to meet them.
whilst the jacksonvile is destroyed in the battles between US and EU soldiers.
Jacksonville is also a major USN base. which is why it was taken.
the EU and US armadas in the south atlantic have a major battle, which I give to the US, and the remnants of the us fleet steam north to and attack the EU fleet and supply ships in the atlantic.
thats so far.
let me know what you think.
I've no idea how effective or not effective special forces might be in crippling a country. I'm predicating my invasion on the fact that they could cause major disarray not just to military bases, but transport links, power supply etc.