US Ambassador to the United Nations Nikki Haley unveiled on Thursday "undeniable" evidence that proves Iran is violating international law by funneling missiles to Houthi militias in Yemen.
The US will now rally other nations to push back on Iran's behavior, she vowed.
"You will see us build a coalition to really push back against Iran and what they're doing.”
She revealed recently declassified evidence including segments of missiles launched at Saudi Arabia from Houthi-controlled territory in Yemen.
The arms included charred remnants of what the Pentagon said was an Iranian-made short-range ballistic missile fired from Yemen on November 4 at King Khaled International Airport outside Saudi Arabia's capital Riyadh, as well as a drone and an anti-tank weapon recovered in Yemen by the Saudis.
"These are Iranian made, these are Iranian sent, and these were Iranian given," Haley told a news conference at a military hangar at Joint Base Anacostia-Bolling, just outside Washington.
Under a UN resolution that enshrines the Iran nuclear deal with world powers, Tehran is prohibited from supplying, selling or transferring weapons outside the country unless approved by the UN Security Council. A separate UN resolution on Yemen bans the supply of weapons to Houthi leader Abdul Malek al-Houthi and others.
Haley said the missile parts bear markings showing they originate in Iran and that they have technical specifications that are specific to Iranian-manufactured weapons.
Haley stressed it proves "blatant violations" of UN Security Council resolutions while the international community was "looking the other way" because of the nuclear deal.
The Pentagon offered a detailed explanation of all of the reasons why it believed the arms came from Iran, noting what it said were Iranian corporate logos on arms fragments and the unique nature of the designs of Iranian weaponry.
That included the designs of short-range "Qiam" ballistic missiles. The Pentagon said it had obtained fragments of two Qiam missiles, one fired on November 4 against the airport and another fired on July 22.
The Pentagon cited corporate logos it said matched those of Iranian defense firms on jet vanes that help steer the missile's engine and on the circuit board helping drive its guidance system. It also said the missile's unique valve-design was only found in Iran.
Iran, it said, appeared to have tried to cover up the shipment by disassembling the missile for transport, given crude welding used to stitch it back together.
"The point of this entire display is that only Iran makes this missile. They have not given it to anybody else," Pentagon spokeswoman Laura Seal said. "We haven't seen this in the hands of anyone else except Iran and the Houthis."
A new UN report found that the July 22 and November 4 missiles fired at Saudi Arabia by the Houthis appeared to have a "common origin."
The Pentagon put on display other weapons with designs it said were unique to Iran's defense industry. It pointed to a key component of a Toophan anti-tank guided missile and a small drone aircraft, both of which it said were recovered in Yemen by the Saudis.
It also showed components of a drone-like navigation system like the one the Pentagon says was used by the Houthis to ram an exploding boat into a Saudi frigate on January 30. The United Arab Emirates seized the system in late 2016 in the Red Sea, the Pentagon said.