At a news conference in a hanger at a military base in Washington, Nikki Haley presented recently declassified evidence including segments of missiles launched at Saudi Arabia from Houthi-controlled territory in Yemen.
In an earlier tweet on Thursday, the chief diplomat also compared Haley's allegations against Iran to those of former US secretary of state Colin Powell who alleged in 2003 that former Iraqi dictator Saddam Hussein was hiding weapons of mass destruction in order to make a case for attacking the country.
It welcomed the fourth United Nations report on the implementation of resolution 2231 which it condemned the blatant and hostile Iranian meddling in Yemen's internal affairs.
Nikki Haley, the US ambassador to the United Nations, stood in front of a rusty hunk of metal Thursday and accused Iran of exporting weapons to rebels in Yemen, a violation of U.N. resolutions.
"This purported evidence, put on public display today, is as much fabricated as the one presented on some other occasions earlier".
But while Haley described the material as "irrefutable" evidence of the "undeniable fact that the Iranian regime's behavior is growing worse", Iran's government immediately claimed that the Trump administration was brazenly lying.
On social media, Iran's Foreign Minister Mohammad Javad Zarif compared Haley's speech to that of her predecessor, Colin Powell, at the United Nations in 2003, when he presented flawed evidence purporting to show Iraq's weapons of mass destruction program as a basis for the U.S. invasion there one month later.
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"The Iranian government issued a statement Thursday denying that a presentation earlier in the day by the US represented proof that they'd been sending arms to the Shia Houthis in Yemen in a bid to resist the USA -backed Saudi invasion, saying it was a 'fabrication".
Its ballistic missiles and advanced weapons are turning up in war zones across the region.
He serves on the boards of the Harvard International Review, the Harvard International Relations Council and the US-Middle East Chamber for Commerce and Business.
In addition, the deputy commander of the IRGC's Qods Force, Esmail Ghani, said: "Those defending Yemen have been trained under the flag of the Islamic Republic."Statements by the United Nations and USA, as well as reports by intelligence agencies, are significant because they corroborate and substantiate what Saudi leaders have previously pointed out, that Houthi missiles targeting Riyadh were made by Iran".
The Iranian weapons were retrieved by USA partners, namely Saudi Arabia and the United Arab Emirates, both of whom support forces in Yemen which stand in opposition to the Houthis and who have been battling against the group since the start of the war in 2014.
"Following a series of baseless accusations against the Islamic Republic of Iran in the past 10 months, the U.S. Ambassador to the United Nations once again today took the same line accusing the Iranian government of supplying the missile that hit Saudi Arabia on November 4th - an accusation that we categorically reject as unfounded and, at the same time, irresponsible, provocative and destructive", Iran said. She further said that its components included stamps of Iranian manufacturers. He also called on Iran to "carefully consider the concerns raised by other participants in the plan".