Commentary It’s that time of year when China announces its defense budget. This year, defense spending is set to increase 7.1 percent (1.45 trillion yuan or $230 billion) after last year’s 6.8 percent rise, and a 6.6 percent increase the year before that. But these figures are almost meaningless. Perhaps Beijing only issues them as a favor to the Pentagon and U.S. think tanks. How’s that? In the United States, a defense budget works as follows: Congress authorizes a certain amount of money to be spent on “defense,” say, $728.5 billion. The Department of Defense and the military services then have to live within that amount. If they overspend, they’re “Out of Schlitz,” to borrow an old beer commercial jingle. And they’ll have to wait until next year, or else beg for something extra. It’s not so different from our personal budgets and how we manage our income and expenses. So it sounds familiar to …