The Trump administration has asked U.S. embassies to press foreign governments to join a new international coalition called the "Maritime Freedom Construct (MFC)."
The coalition is aimed at restoring the freedom of navigation through the Strait of Hormuz, according to an internal State Department cable seen by the Wall Street Journal (WSJ) and Reuters.
U.S. Secretary of State Marco Rubio approved the initiative, which combines the State Department's diplomatic coordination with U.S. Central Command (CENTCOM) in real-time maritime domain awareness.
The cable, dated April 28, instructs U.S. diplomats to deliver the demarche verbally to partner nations by May 1. It asks governments whether they wish to be "diplomatic and/or military partners" of the MFC.
"Your participation will strengthen our collective ability to restore freedom of navigation and protect the global economy. Collective action is essential to demonstrate unified resolve and impose meaningful costs on Iranian obstruction of transit through the Strait," the cable states.
Participation could take the form of diplomacy, information sharing, sanctions enforcement, naval presence or other forms of support.
"We welcome all levels of engagement and do not expect your country to shift naval assets and resources away from the existing regional maritime constructs and organizations," the cable stated.
The MFC is structured as a joint initiative of the State Department and the Pentagon.
The State Department "will serve as the diplomatic operations hub" for partner countries and the shipping industry, while CENTCOM, operating from its Florida headquarters, "will provide real-time maritime domain awareness" for commercial shipping and coordinate information sharing between partner militaries.
The cable explicitly distinguished the MFC from Trump's Maximum Pressure campaign and from the ongoing peace negotiations.
It also said the construct "would be complementary to other security maritime task forces, including the maritime planning effort the U.K. and France are leading."
The demarche is not to be delivered to Russia, China, Belarus, Cuba and "other U.S. adversaries," the cable states, drawing a clear geopolitical boundary around the coalition's intended membership.
Speaking from the Oval Office on Wednesday, President Trump told reporters: "The blockade is genius, OK, the blockade has been 100% foolproof."
He said he was willing to maintain the blockade and the war "unless they agree that there will be no nuclear weapon."
The Wall Street Journal previously reported that Trump told aides on Monday to prepare for an extended blockade until Iran abandoned its nuclear program.
The push for a multilateral coalition stood in some tension with Trump's earlier statements telling European allies to "build up some delayed courage, go to the Strait, and just take it" and his declaration that NATO was "a paper tiger" that "didn't help us."