President Trump directed the U.S. to test nuclear weapons after claiming other countries are, but experts warn about the global impacts of an escalated arms race and what it would do to the American West.

Donald Trump ordered the Pentagon to immediately begin testing of the US nuclear arsenal on Thursday, hours after Russia announced it had tested a nuclear-capable underwater drone.

Moves toward renewed explosive tests of nuclear warheads would further endanger the treaty that for decades has constrained all but a handful of countries from carrying them out.