By Courtney McBride

The United States has notified the United Nations Security Council of its intent to reimpose U.N. sanctions against Iran that were suspended as part of a 2015 international nuclear agreement, setting the stage for a legal dispute among member states.

Secretary of State Mike Pompeo communicated the U.S. position in a Thursday afternoon meeting with U.N. Secretary-General António Guterres and was scheduled to address the media later.

The process, known as "snapback," allows any of the nations that were party to the 2015 nuclear accord between Iran and six world powers to call for the reimposition of U.N. sanctions as a result of Tehran's "significant nonperformance" of its commitments under the deal.

While the U.S. withdrew from the agreement in May 2018, the Trump administration contends that it retains the legal authority to urge a restoration of the sanctions. A memo drafted by the State Department's legal adviser and circulated to members of the Council argues that the U.S. has "an explicit right" to initiate snapback.

Mr. Pompeo's action, which Trump administration officials have telegraphed for months, follows Friday's defeat of a U.S. bid to extend a conventional-arms embargo on Iran. The ban on sales of certain weapons by and to Iran was originally imposed on an indefinite basis in 2007, but was time-limited as part of the 2015 nuclear accord. It is due to expire on Oct. 18.

In a statement announcing Mr. Pompeo's visit to the U.N., State Department spokeswoman Morgan Ortagus said that snapback would extend the arms embargo and impose other obligations, "including the requirement that Iran suspend all enrichment-related activities."

Mr. Pompeo said Wednesday that the U.S. offering would constitute "a fully valid, enforceable U.N. Security Council resolution," and that he expected all nations to comply with it. He said in a Fox News interview that European countries have privately expressed support for an extension of the conventional-arms embargo but refused to support the U.S. resolution as a result of their desire to preserve the nuclear deal.

President Trump's administration has waged a campaign of "maximum pressure" against Iran, seeking to alter Tehran's behavior through a combination of diplomatic isolation and crippling economic sanctions. The U.S. has designated the nation's Islamic Revolutionary Guard Corps as a foreign terrorist organization, sanctioned individuals and entities doing business with Tehran, and seized cargo from tankers carrying Iranian fuel.

Iran has largely remained in compliance with the 2015 nuclear accord, and has accused the U.S. of seeking to harm the Iranian people and of destabilizing the Middle East through its military interventions.

Other members of the 15-member Security Council now have 10 days to introduce and pass a resolution that would negate the U.S. effort. Barring passage of such a measure, the sanctions would come back into place within 30 days of the U.S. notification.

As a permanent member of the Council, the U.S. wields a veto over resolutions introduced there. The Council's other permanent members are France and the United Kingdom, which abstained from Friday's vote on the arms embargo, as well as China and Russia, which opposed the U.S. proposal. All four countries remain in the nuclear deal, as does Germany, a nonpermanent member of the Council, which also abstained.

Write to Courtney McBride at courtney.mcbride@wsj.com