ISLAMABAD (AP) — President Donald Trump posted Sunday on social media that the U.S. Navy would “immediately” begin a blockade to stop ships from entering or leaving the Strait of Hormuz.

After U.S. officials ended peace talks with Iran in Pakistan, Trump sought to exert more strategic control over the waterway responsible for the transportation of 20% of global oil supplies — hoping to takeaway Iran’s key source of economic leverage in the war.

“Effective immediately, the United States Navy, the Finest in the World, will begin the process of BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz,” Trump posted.

The president added that he has “also instructed our Navy to seek and interdict every vessel in International Waters that has paid a toll to Iran. No one who pays an illegal toll will have safe passage on the high seas.”

The president stressed that Iran’s nuclear ambitions were at the core of the failure to end the war and that the U.S. was prepared to finish the war.

“(A)t an appropriate moment, we are fully ‘LOCKED AND LOADED,’ and our Military will finish up the little that is left of Iran!” Trump posted.