Banks Too Big to Fail, Too Big to Bail Out: Roubini

European governments face the quandary of being unable to afford to bail out banks that are still considered too big to fail, while the global economy is heading for a slowdown in the second half of the year, economist Nouriel Roubini of Roubini Global Economics told CNBC Tuesday.

Governments are running out of ways to counter a "massive slowdown" or the risk of a double-dip recession, Roubini said.

"A year ago we had all these policy bullets," he said. "We could push down rates to zero, we had (quantitative easing), we could do a budget deficit of 10 percent of GDP (or) backstop the financial system." (more)