President Obama has lost the Washington Post – one of his most ardent supporters – and that should trouble him. On Iran, the Post most definitely has much cause for anger. Its reporter is being held by that country on trumped-up charges.

But the Post’s larger point is valid. Iran continues to defy the agreement it signed off on, and international norms, while the president does nothing.

“Iran is following through on the nuclear deal it struck with a U.S.-led coalition in an utterly predictable way: It is racing to fulfill those parts of the accord that will allow it to collect $100 billion in frozen funds and end sanctions on its oil exports and banking system, while expanding its belligerent and illegal activities in other areas – and daring the West to respond,” the Post wrote in an editorial last week. “Unfortunately, the Obama administration’s response to these provocations has also been familiar. It is doing its best to downplay them – and thereby encouraging Tehran to press for still-greater advantage.”

The State Department said it’s “still considering” responses to a ballistic missile launch in October, and a probable launch in late November. Both violated U.N. resolutions.

“In other words, there have so far been none – other than a speech by the U.S. ambassador to the United Nations blaming the Security Council for the lack of action,” the Post complained. “As for the second missile launch, the administration claims to be investigating it, though it likely has in its possession the intelligence necessary to make a judgment.”

Here’s the part that should trouble the president the most:

“It’s not hard to guess the reasons for this fecklessness,” the Post wrote. “President Obama is reluctant to do anything that might derail the nuclear deal before Iran carries out its commitments, including uninstalling thousands of centrifuges and diluting or removing tons of enriched uranium.”

So to be clear, the Post thought Obama is ignoring Iran’s breach of the rules now, in hopes that Iran won’t break the rules later.

But even the Post can no longer ignore Iran’s nuclear intentions.

“The only practical military purpose of the missiles the regime is testing is to carry atomic warheads,” the Post pointed out. “And while missile launches are not prohibited by the nuclear pact itself, the separate resolution banning them remains in effect until the deal is implemented, after which a new resolution takes effect that calls on Iran not to develop such missiles for eight years. By flouting the U.N. resolutions, Iran is clearly testing the will of the United States and its allies to enforce the overall regime limiting its nuclear ambitions.”

In an earlier editorial, the Post pointed out that reporter Jason Rezaian has now been in an Iranian prison for more than 500 days, and that he “is no longer allowed contact with his lawyer.”

Rezaian was never brought up during the negotiations that gave Iran a nuclear future. That was a mistake.

But it’s an even bigger mistake to let Iran continue to flout the rules.