In a short while, Donald Trump will deliver a speech about his next moves on the deal Barack Obama and John Kerry cut with Iran, which he has claimed is the worst deal in his lifetime. As all of the indications have shown thus far, Trump will announce that he’s “decertifying” the pact, meaning that he has concluded it is not in America’s national interests:

Don’t expect Trump to end it outright, however, or force immediate restoration of sanctions. Secretary of State Rex Tillerson announced that Trump would take a more incremental approach to revising the deal — and essentially dump it in Congress’ lap:

Secretary of State Rex Tillerson says President Donald Trump will not withdraw from the Iran nuclear deal or reimpose sanctions, but he will say the pact is not in U.S. national security interests.

Trump is scheduled to give a speech Friday afternoon on the nuclear accord, which he has repeatedly denounced as the worst deal in American history. The plan would allow Trump to keep up his criticism of the deal, while also reassuring U.S. allies that Washington will not walk away from it — at least not immediately.

Tillerson said Friday that Trump would urge Congress to toughen requirements for Iran to continue to get relief from U.S. sanctions. The administration wants Congress also to amend legislation to highlight troubling non-nuclear Iranian behavior not covered by the deal.

Trump also wants to force the other nations involved in the original P5+1 efforts to come back to the bargaining table, Tillerson told the media. He may offer them a Hobson’s choice of renegotiation or nothing, but that the US will not bother making a case that Iran’s not in compliance with the deal as it is:

“We don’t dispute that they’re under technical compliance,” Secretary of State Rex Tillerson said of the Iranians. He suggested the president’s decision is based on an assessment of Iran’s overall conduct, balanced against the sanctions relief granted by the agreement.

By refusing to certify the deal, Tillerson said the president hopes to signal to Tehran and other international players that it’s time to come back to the bargaining table.

“This is the pathway we think provides us the best platform from which to attempt to fix this deal,” Tillerson said.

The immediate effect, though, will be to force Congress to conduct a 60-day review of the agreement, and to do … something. Sen. Bob Corker (R-TN), with whom Trump has feuded of late, announced earlier that he’s ready to take action to support Trump’s decision:

Olivier Knox reports that one key piece of Corker’s bill would be to tie the accord to Iran’s missile program:

No matter the process, though, eventually Trump and Tillerson have to get our European allies to reopen the matter with Iran. If they refuse, we end up going it alone, and our sanctions will have much less effect while Iran is freed up to openly pursue nuclear weapons. If they agree, Russia and China will likely balk. But even if Trump and Tillerson manage to get the entire band back together, it’s unclear what leverage remains for enforcement. Iran has already recovered its trillion-dollars-plus in assets, and has access to oil markets for two years, during which they have no doubt prepared for the eventual reapplication of sanctions. We’d be starting from scratch, and on an issue that our partners clearly have little interest in pursuing — with the exception of Israel and the Sunni Arab states.

That doesn’t mean we shouldn’t pursue the security interests of the US and our regional allies. But it does mean it’s a lot less likely to work … and for that, we can thank Obama and Kerry.