President Trump ordered the Pentagon to reduce planned joint military exercises with South Korea, an ally the US has long worked with to deter North Korea.
The EU Council renewed its sanctions on Iran, which were imposed over Iran sending attack drones and missile parts to Russia for the war in Ukraine.
President Donald Trump says he will declare the Strait of Hormuz, a narrow sea passage between Iran and the Arabian Peninsula, part of United States territory.
President Trump said the aircraft carrier USS Abraham Lincoln, which has spent a record nearly nine months at sea backing US operations against Iran, will keep deploying, dismissing concerns about sailors' mental health.
Traffic through the Strait of Hormuz, the narrow waterway between Iran and Oman that carries much of the world's oil, has slowed further, Reuters reports, as the United States threatens new economic penalties on Iran.
The US Defense Secretary said the Navy's blockade around the Strait of Hormuz, a narrow sea passage next to Iran through which much of the world's oil passes, can go on indefinitely.
The United States is sending a second aircraft carrier, the USS George Washington, to join the USS Abraham Lincoln near Iran, giving it two carrier groups in the region.
Iran has said it will only reopen the Strait of Hormuz, a narrow sea passage that much of the world's oil ships through, if the United States lifts its economic sanctions on Iran.
President Donald Trump confirmed he personally approved a Secret Service request to switch the aircraft he was flying during this month's NATO summit in Turkey, after a threat linked to Iran targeted Air Force One, the plane presidents normally use.
According to The Washington Post, Donald Trump did not leave this month's NATO summit in Turkey the way he has publicly described.
President Trump said the United States is taking a low-key approach in its standoff with Iran, preferring economic pressure over military action.
Ukraine bought 70 ATACMS, a US-made long-range missile, from Turkey instead of the US.