US Federal Reserve Chair Jerome Powell says that uncertainty in the world's biggest economy should be much lower a year from now, as President Donald Trump's policies, including steep tariffs, take effect. "Uncertainty will decline," the central bank chief tells an event in Virginia. "Fast-forward a year from now, the uncertainty should be much lower. The actual effects of the policies should then be pretty manifest and clear." [COMPLETES VIDI397L662_EN, VIDI397K9CP_EN AND VIDI397E662_EN] IMAGES AND SOUNDBITES