Nikki Haley, U.S. ambassador to the United Nations, will attend a meeting Wednesday on the Iranian nuclear deal as part of the U.N. General Assembly, a U.S.official confirmed.

It's a notable addition to the meeting since the European Union had invited foreign ministers who were party to the deal. Secretary of State Rex Tillerson was already slated to attend.

This will be the highest-level known encounter between the Trump administration's national security team and Iranian officials so far.

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During his first address to the annual gathering Tuesday, Mr. Trump blasted the Iranian nuclear deal that the Obama administration helped negotiate.

"The Iran deal was one of the worst and most one-sided transactions the United States has ever entered into. Frankly, that deal is an embarrassment to the United States, and I don't think you've heard the last of it, believe me," Mr. Trump said.