The U.S. national debt has reached an ominous milestone, surpassing the size of the entire U.S. GDP for the first time since World War Two, USA Today reported.

The amount of money the federal government owes to external creditors and its own trust funds, largely Social Security, now tops $15.23 trillion whereas the value of all goods and services the U.S. economy produces in one year is estimated at $15.17 trillion.

Long-term forecasts say the U.S. national debt will continue to grow faster than the economy, which would have to expand by at least 6 percent a year to keep pace.

The U.S. national debt topped the size of the economy for three years during and after World War Two. It fell to slightly over 30 percent of GDP by 1981 and then started a steady climb under President Ronald Reagan, doubling in the next 12 years.

Recession and economic stimulus measures have caused the national debt to soar under President Barack Obama.

Among advanced economies, only Greece, Iceland, Ireland, Italy, Japan and Portugal have debts exceeding the size of their economies. Greece, Ireland and Portugal needed large bailout packages to stave off default.

The U.S. White House and Congress agreed last summer to cut about $1 trillion in federal spending over 10 years. An additional $1.2 trillion in automatic cuts to domestic programs and national defense will begin next year, if lawmakers fail to agree on a better spending cut plan.

Obama unveiled a new defense strategy on Thursday that seeks to reduce the country’s armed forces in line with almost $500 billion in cuts to the U.S. defense budget.

"Our military will be leaner but the world must know – the United States is going to maintain our military superiority with Armed Forces that are agile, flexible and ready for the full range of contingencies and threats," Obama told a press conference at the Pentagon.