Tensions are on the rise between the United States and Iran in a standoff over new economic sanctions and Iran’s threat to block a Gulf passageway in response. Iran said this week it would close off the Strait of Hormuz if President Obama enacts new economic sanctions targeting Iran’s oil exports. The sanctions were passed as part of a congressional measure targeting Iran’s alleged nuclear activities and now await Obama’s signature. About one-fifth of the world’s oil is said to pass through the Strait of Hormuz. On Wednesday, the U.S. Navy’s Fifth Fleet, based in Bahrain, said any disruption of the strait “will not be tolerated.” Iran meanwhile says it has video of a U.S. aircraft carrier during a naval exercise near the strait.