US ambassador to the United Nations Nikki Haley on Thursday will present evidence that Iran has "deliberately violated" its international obligations, the Pentagon said.
Haley, who is appearing at a Washington military base, will hold a press conference on Iran's "ongoing destabilizing activities in the Middle East and elsewhere," the Pentagon said in a statement.
"During the briefing, Ambassador Haley will offer irrefutable evidence that Iran has deliberately violated its international obligations and has tried and failed to cover up these violations," the statement read.
Haley has called on the UN Security Council to take a tougher stance toward Iran, accusing Tehran of making illegal arms deals in Yemen, Lebanon and Syria.
A confidential report to the council says UN officials had examined debris from missiles fired at Saudi Arabia which pointed to a "common origin" but there was no firm conclusions as to whether they came from an Iranian supplier.
The report from UN Secretary-General Antonio Guterres, which was obtained by AFP, said the officials were still analyzing the information.
A separate team of UN experts who inspected the missile fragments during a visit to Riyadh last month found a possible link to an Iranian manufacturer, the Shahid Bagheri Industrial Group, which is on the UN sanctions blacklist.
The experts, who report to the sanctions committee, found a component marked by a logo similar to that of the banned group, which is a subsidiary of the Iranian Aerospace Industries Organization.
In his report, Guterres said officials had seen the logo but that they were still analyzing the information.
Recent Iranian missile launches have triggered US sanctions and accusations they violate the spirit of a 2015 nuclear deal between Tehran and major powers.
A Saudi-led coalition fighting rebels in Yemen imposed a blockade of Yemen's air and sea ports and borders after the missile was fired at Riyadh, citing concerns that weapons were being smuggled into Yemen.