Behind the gradual and relatively small rise in the U.S. unemployment rate in recent years are a couple of less-closely followed labor market indicators that are flashing yellow for recession risk, according to research published on Monday by the Federal Reserve Bank of San Francisco. The analysis suggests a measure of hidden weakness in what has widely been seen as a solid labor market that is now coming under pressure from the Trump administration's massive tariffs, which have raised the twin risks of higher inflation and higher unemployment.