Warren Buffett has made billions since the financial crisis by investing in U.S. banks, including Bank of America (NYSE: BAC),
The Oracle of Omaha has even guaranteed the safety of U.S. banks.
"The banks will not get this country in trouble, I guarantee it," Buffett told Bloomberg News. "Our banking system is in the best shape in recent memory."
Buffett, CEO of Berkshire Hathaway (NYSE: BRK.A, BRK.B), says U.S. banks are safe because they have increased capital ratios, sold risky assets, cut unnecessary jobs and bolstered their balance sheets.
But while the U.S. banking system might be in better shape than it was five years ago, it is nowhere near fixed. And banks could cause another crash.Here's why.