President Donald Trump is “very serious” about his plan to impose a 20% toll on cargo transiting through the Strait of Hormuz, a White House official told Semafor, asserting that it’s a plan he’s wanted to move forward with for months.

The president has long flirted with the idea of charging a toll, wondering back in April “why shouldn’t” his administration do so and threatening to impose fees in June if a deal with Iran was not completed within a 60-day period.