The Prussian military theorist Von Clausewitz said that war was the continuation of politics by other means; some have since substituted the word "economics" for "politics".
But such is the complexity of modern industrial society, and the horrific potential of modern military technology, that we may invert the relationship: economic ownership and infrastructure may be the new weapons with which to wage war.
It is not hard to see the power potential in China's increasing stake in the US economy - not only US government bonds, but increasingly, other assets such as equities. Already, the bond market feels the jerk of the chain, and within the last couple of years Britain has stepped in to provide some much-needed slack to America. But the growth of "sovereign wealth funds" could see future governments using their investments to interfere in the equity markets, too. What price free trade then?
And there are other gaps in the armour. For example, America's recent allegations against China of cyber-warfare have highlighted our daily dependence on electronic technology.
Two Chinese colonels, Qiao Liang and Wang Xiangsui, have produced a book examining such possibilities: "Unrestricted Warfare" (1999). Some translated extracts are available here, and the Wikipedia article is here.
This is not to say that China is actually hostile; only that, like the rest of us, she has her own agenda, and her own contingency plans. Much of warfare is not outright battle, but the use of threats and potential threats to gain strategic advantage. Pushing your opponent into desperation can backfire disastrously. As Sun Tzu said, "To a surrounded enemy, you must leave a way of escape."
But we must recover our economic balance, or risk having the imbalance used against us.