At his UNGA address, Donald Trump has warned that the U.S. could “annihilate” Iran quickly if Tehran refuses to reach a deal, while predicting that oil prices will soon come “plummeting down.” Trump's remarks at the UN General Assembly come as markets watch the Iran war, the Strait of Hormuz and prospects for U.S.-Iran diplomacy, with Brent crude recently falling below $100 a barrel on hopes of easing tensions.