Know how you can tell the Trump administration’s tough approach on Iran is working? Tehran is acting out in a bid to remove the pressure.

Iran’s rulers pointedly announced Monday that they’ll soon cross a red line of the 2015 nuclear deal by exceeding its limit on stockpiles of highly enriched uranium. This comes a week after an attack on two fuel tankers in the Gulf of Oman — attacks that the Trump administration has laid at the feet of Iran’s Revolutionary Guard, though Tehran says it’s been framed.

As Eli Lake noted in Wednesday’s Post, this is not a sudden aggressive turn by Iran: Tehran was intervening in both Yemen and Syria even as it was negotiating the nuke deal, and has kept it up since. The difference is that the latest moves more directly threaten European comforts.

Breaching the nuke deal is plainly intended to freak out European leaders who desperately cling to faith in that accord (even though it gave Iran free rein to go fully nuclear within the decade). The Gulf attacks, meanwhile, are a transparent hint that Tehran stands ready to disrupt world oil markets if it’s not appeased.

It’s all meant to get panicked allies and CEOs to push the White House to reverse course, and relax the sanctions that have reduced Iran’s oil sales to a trickle, pushing its economy toward collapse.

Ali Shamkhani, secretary of Iran’s Supreme National Security Council, made the strategy explicit Tuesday: “If a broad spectrum of countries decide to stand against the illegal blackmailing and bullying by the US, we can make the US retreat.”

But the threats are empty: Even rapid nuclear progress won’t save the Iranian economy before the regime must bend or collapse. And Washington has defeated Tehran’s bid to close the Gulf to tankers before, and if need be will do it again. Plus, the world oil supply is far less dependent on Gulf traffic than in the past, thanks in part to the US fracking revolution.

Certainly, President Trump isn’t blinking: His response to the attacks was to order more US forces to the region.

Keep it up, Mr. President.