The U.S. special representative for Iran is traveling to the United Nations to update permanent members of the Security Council on U.S. policy toward Iran, as Washington looks to step up pressure on Tehran.
The U.S. State Department said in a statement that Brian Hook would be in New York on April 30 and May 1 for the meetings.
"He will underscore the importance of holding Iran accountable for its defiance of UN Security Council resolutions on the development and testing of ballistic missiles," the statement said.
It said he will also reiterate the need to fully implement all relevant UN Security Council resolutions related to Iran, "including the enforcement of the Council's legally binding travel restrictions and arms embargoes."
Washington has taken a hard line against Iran since President Donald Trump took office in January 2017.
Trump last year pulled the United States out of a landmark 2015 nuclear agreement that Tehran signed with six world powers, receiving relief from sanctions in return for curbs on its nuclear program.
In withdrawing, Trump said the accord was "fatally flawed" because it did not address Iran's ballistic-missile program or Tehran's alleged state sponsorship of terrorism.
Tehran has said its nuclear program is for civilian purposes and denies that it funds militant groups in the region.
Washington on April 22 ended six months of waivers that allowed Iran's eight largest customers to continue importing some Iranian oil despite the renewed U.S. sanctions.
The administration has said its aim is to reduce Iranian oil exports to zero.
Iran has said it will continue to export oil despite the increasing pressure by Washington.
Trump earlier this month designated Iran's Islamic Revolutionary Guards Corps (IRGC) a "foreign terrorist organization," the first time the United States has designated a state entity of another government as such.
That brought a response from Tehran, which on April 30 said President Hassan Rohani had signed a bill into law declaring all U.S. forces in the Middle East terrorists and labeling the U.S. government a sponsor of terrorism.
It was not immediately clear what impact the law might have on U.S. forces’ operations in the Middle East.
Meanwhile, the United States earlier this year criticized a move by Germany, France, and Britain to launch a new trade mechanism that allows foreign firms to conduct business with Tehran.
The so-called special-purpose vehicle, will help European firms with legitimate business interests to use barter techniques to conduct business in Iran, European officials said.
U.S. Special Envoy To Brief UN Security Council On Iran Policy