Bush said today he wants to send more troops into Iraq. Hmmm. The war is already costing more than $2 billion a week. So how, exactly, are we going to afford the extra 20,000 troops Bush wants?

Our soldiers comprise what’s called an “all-volunteer” army. But the job of soldiering is “voluntary” the same way any paid job is voluntary. You’re not forced to do it. You’re paid to do it.

Since Richard Nixon ended the draft in 1973, most of the people who join the military do so because it’s the most attractive job available to them. Some are motivated by patriotism, of course, but let’s not kid ourselves. People facing a choice between a job in the private sector that’s near home and safe, and one in the military that’s thousands of miles away and may not be safe, will choose to remain civilians – unless the military job pays more. And for any given age and level of education, it does.

When the unemployment rate is relatively low, as now (note I said “relatively” – there are still millions of people without jobs), the Pentagon has to pay even more to attract additional recruits. That’s why the defense appropriations continue to raise military pay 3.1 percent a year, considerably faster than civilian pay is rising.

Cash isn’t the Pentagon’s only lure. The military is also offering signing bonuses up to $30,000 for jobs in high demand. You can get up to a $150,000 cash bonus for re-enlisting if you’re with the Special Forces. And all recruits are eligible for up to $50,000 to offset the costs of higher education and up to $65,000 to pay back college loans. Not to mention generous housing, child care, and health benefits.

But not even all this is enough. According to Congress’s General Accountability Office, the Pentagon has fallen behind its targets for recruiting and re-enlisting soldiers for vital combat positions. According to military experts, the war in Iraq and Afghanistan is scaring many potential recruits away. No surprise, here. Even though only a portion of our 1.4 million active-duty personnel serve in a war zone or hardship area, the job of a soldier is far more dangerous these days.

It’s the law of supply and demand. If we want more people to sign up, and stay signed up, we’ve got to pay them even more. But here’s the catch. Try paying them much more and we run into an incontrovertible obstacle called the federal budget deficit.

If you haven’t heard, the deficit is out of control. There’s no money left for substantially higher pay and benefits for the troops. So where will the extra troops come from? Will the White House try to reinstate the draft?