That was what he told Post readers in his column. He talked about President Obama's deficit commission as "the last hope for gaining control of government spending," telling readers that:
"The problem is so big as to seem insurmountable: $13 trillion of debt, now equivalent to 60 percent of gross domestic product. In 10 years, that is projected to increase to 90 percent of GDP, at which time we'll be making $1 trillion a year in interest payments."
People with more familiarity with numbers would note that the country has had larger debt to GDP ratios in times past. They would also point out that that the $1 trillion in interest payments is less than 5 percent of projected GDP in ten years. The government faced the same interest burden in the early 90s.
Furthermore, unless the Fed acts irresponsibly (a big if, it did allow the $8 trillion housing bubble that wrecked the economy), it will own much of the government's debt. In this case, the interest will be paid to the Fed, which in turns will rebate it to the Treasury leaving no net interest burden. Currently the Fed is rebating an amount equal to almost 40 percent of the interest paid by the Treasury. Reporters at most newspapers would be expected to understand this relationship.
It is also not clear what Milbank thinks is out of control about government spending (maybe he sees flying saucers also). Government spending has mostly increased to support the economy in response to the worst downturn since the Great Depression. His column suggests that he may be unaware of this downturn.