So, the guy behind the world’s largest bond fund is dumping U.S. government debt.

Got your attention yet?

Bill Gross of Pacific Investment Management Co. (PIMCO) is no great fan of U.S. government debt to start with: His fund also zeroed out its holdings of Uncle Sam’s IOUs back in 2009, but had added some back into the portfolio. No more. He’s not buying what Washington is selling, and he’s urging others to dump U.S. bonds, too. Bloomberg reports:

Gross in his February commentary urged investors to reduce holdings of Treasuries and U.K. gilts and buy higher-returning securities such as debt from emerging-market nations. “Old-fashioned gilts and Treasury bonds may need to be ‘exorcised’ from model portfolios and replaced with more attractive alternatives both from a risk and a reward standpoint,” Gross wrote.

So, what’s wrong with U.S. government debt? With deficits running at insane levels but interest rates still low, the risk-reward ratio is out of whack, even compared to “emerging-market” countries — read: those Third World regimes whose farcical finances we used to regard with a mixture of scorn and pity, until we began emulating them. All the money-printing down at the Fed is taking a toll:

Gains in so-called headline inflation matter more for the U.S. economy than Fed Chairman Ben S. Bernanke suggests and rising oil prices may cut U.S. gross domestic product by a quarter to half a percentage point, Gross said March 4 in a radio interview on “Bloomberg Surveillance” with Tom Keene.

“Bernanke tends to think this doesn’t matter — at least in terms of headline versus the core — we do,” Gross said.

What this means, of course, is pressure on the U.S. government to offer higher interest rates on its bonds. Gross says that the rates need to go up about 1.5 percent to reflect market realities. And market realities, ignored for the past few years, are going to start reasserting themselves as “quantitative easing” ends and the Fed stops buying U.S. debt that the markets don’t want.

As things stand, interest on the debt (at about 6 percent of all federal spending) is equal to about one-third of all discretionary spending combined (about 19 percent of the budget). Current forecasts have debt-service costs alone amounting to nearly $1 trillion by 2020, consuming 20 percent of all federal tax revenues. That’s a vicious circle: Bigger deficits add to the total debt, which drives up the cost of debt service, which creates bigger deficits, shampoo, rinse, repeat, and wake up in Argentina circa 1999–2002.

Which gets us back, as usual, toward the one inevitable, undeniable fact of American life at this moment: The major entitlement programs — Social Security, Medicare, Medicaid — other “mandatory” spending, national defense, and interest on the debt make up more than 80 percent of federal spending. Everything else put together accounts for less than $1 in $5 of government outlays. Assuming we don’t default on our national debt, interest on the debt is the one spending item that is truly off the table. Even if we cut national-defense spending to zero, that would only get us just over halfway toward eliminating the trillion-dollar deficit headed our way in 2012. (We aren’t cutting national-defense spending to zero.) Meaning that major reform of the entitlement programs is not optional. It is do or die.

Bernanke & Co. have baked inflation into this cake, and catastrophic state and local finances mean that Washington really can’t pass off its spending schemes onto the governors, mayors, and state legislatures.

You may think the Ryan Roadmap looks harsh and disruptive. But we simply must start dealing with these things right now, while we have some resources, some options, and some time. It will be much more harsh and disruptive to try to deal with these things after the fiscal crisis is upon us, when inflation is skyrocketing, unemployment is through the roof, and the markets start demanding a very high premium to finance the debt of Washington, the states, and the cities, if indeed investors are willing to do so at all.

We are in an extraordinarily dangerous period, one that calls for real leadership in Washington, where the geniuses in charge are currently locked in a death struggle over whether to cut nothing or next to nothing.

NPR? Foreign aid? Food stamps? That isn’t going to do it. The fact that we’re even having a discussion about whether we have to federally subsidize experimental opera companies in Topeka suggests that the message has not quite hit home. Maybe when the Social Security checks stop coming, Americans will notice. Which is to say, when it’s too late.

To be clear, PIMCO in and of itself is not disastrous — it is just a mile marker on the road to Fiscal Armageddon. But it is one worth noting.

— Kevin D. Williamson is a deputy managing editor of National Review and author of The Politically Incorrect Guide to Socialism, just published by Regnery. You can buy an autographed copy through National Review Online here.