(Wall Street Journal) -- The 2015 Iran nuclear agreement faces a potentially fateful week, with a series of deadlines awaiting President Donald Trump as Tehran reacts to recent "antigovernment protests" [riots].

Mr. Trump is expected to again notify Congress he doesn’t believe the Iran deal is in the best interest of the U.S., restating a well-known position. More important, Mr. Trump will have several opportunities starting Wednesday to refuse to extend U.S. sanctions relief to Iran under the deal, which would put Washington in breach of its terms.

To stay in the deal, Mr. Trump must periodically agree to waive penalties imposed under a variety of U.S. statutes. In exchange for sanctions relief from the U.S., the United Nations and other countries, Iran agreed to curb its nuclear program.

The recent protests in Iran have added to the uncertainty, as Mr. Trump has backed protesters while denouncing the economic benefits he says the nuclear agreement has provided to Iran’s government.

While Mr. Trump could seize on the protests as a basis for rejecting the sanctions waivers, he could also sign the waivers while taking other steps to punish Iran.

Many of Mr. Trump’s advisers are critical of the nuclear deal but have urged Mr. Trump to remain a party to it while looking for additional ways to confront Iran. 

Secretary of State Rex Tillerson and Defense Secretary Jim Mattis are among advisers who have publicly taken that position.

Mr. Mattis declined on Friday to tell reporters at the Pentagon whether his advice had changed, but said, “I just don’t think the protests will have any influence over my advice to the president one way or another.”

Mr. Trump is likely to introduce additional sanctions unrelated to the nuclear accord next week as these deadlines come up, Mr. Tillerson said Friday. “They will be coming,” he said in an interview on CNN.

Other advisers said Mr. Trump appears on track to extend the sanctions relief, but cautioned that they don’t know what he is likely to do.

In October, Mr. Trump threatened to pull out of the accord unless Congress and European allies agreed on ways to address Iran’s ballistic missile program and to ensure restrictions on Iran’s nuclear activities continue after provisions of the deal expire in future years.

Since then, the Trump administration has consulted with lawmakers and European officials on an amendment to a 2015 U.S. law that gives Congress oversight of the nuclear deal.

People familiar with the discussions said the goal would be for advisers to present Mr. Trump with legislation that will allow him to make good on a pledge to fix the deal.

The discussions have touched on ways to allow for U.S. sanctions on Iran’s ballistic missile program and reduce the frequency with which the president must certify

Iran’s compliance with the deal from quarterly to perhaps once or twice a year, along with other areas of concern.

Officials are also debating when and how sanctions could be reimposed if Tehran undertakes certain nuclear activities.

Several drafts of the legislation have circulated, but there is no final bill yet, the people familiar with the discussions said. Negotiations aren’t expected to wrap up before Mr. Trump must decide whether to extend sanctions waivers, officials said.

Key players in the negotiations include Sen. Bob Corker (R., Tenn.), the chairman of the Senate Foreign Relations Committee, Sen. Ben Cardin (D., Md.), the top Democrat on the committee, and Sen. Tom Cotton (R., Ark.), a close congressional adviser to Mr. Trump on foreign policy.

A Capitol Hill aide familiar with Mr. Cotton’s thinking said the legislation has a long way to go before he would sign on.

Mr. Corker and Mr. Cardin met with Lt. Gen. H.R. McMaster, the White House national security adviser, on Thursday to discuss the amended legislation.

Mr. Corker told reporters on Wednesday that it is important for Mr. Trump to know progress is being made on the legislation as he is weighing what to do about the deal.

European officials have said that they would continue to abide by the accord and stick with it, whether or not the U.S. continues to do so.

Yet any move by the U.S. to reimpose sanctions would mean European companies could face penalties for doing business in Iran.

“The real issue isn’t what diplomats in Paris, Berlin, Rome or Brussels do, it’s what would French, German, Italian or Belgian companies do in response to these moves,” said Mark Dubowitz, chief executive of the Foundation for Defense of Democracies and a critic of the Iran deal who has advised the administration.

(Photo: ANDREW HARNIK/ASSOCIATED PRESS)