The U.S. has accused Iran of stepping up violations of a UN ban on arms exports by increasingly supplying weapons to militant groups across the Middle East and continuing its missile program.
In a November 29 presentation at a military base in Washington, Brian Hook, the U.S. special representative for Iran showed reporters weapons and fragments of weapons seized in Afghanistan, Bahrain, and Yemen that it said are evidence Iran is a "grave and escalating threat" that must be stopped.
The presentation, the second such one in the last year, is part of U.S. efforts to increase pressure on Tehran to halt what Washington calls "malign activities" in the region.
Iran has denied such accusations in the past.
The U.S. withdrew from a 2015 nuclear deal with Iran in May and reinstated tough sanctions that had been lifted under the accord.
"The Iranian threat is growing, and we are accumulating risk of escalation in the region if we fail to act," Hook told reporters.
Hook displayed rockets, missiles, small arms and debris from an Iranian drone that he says were intended for Huthi rebels in Yemen, Shi'ite militants in Bahrain, and the Taliban in Afghanistan.
The centerpiece of the display was what Hook said is a Sayyad-2 surface-to-air missile system that the Saudis had intercepted in Yemen this year. He said Persian writing along the white rocket's side helped prove it was Iranian made.
"The inventory in this display has expanded since December. This is a function of Iran's relentless commitment to put more weapons into the hands of even more of its proxies, regardless of the suffering," he added.
"I haven't heard anybody say this is a political stunt. This is simply putting out in broad daylight Iran's missiles and small arms and rockets and UAVs [unmanned aerial vehicles] and drones," Hook said after being asked whether the weapons display was done for propaganda purposes.
The material shows Iran is determined to send "even more weapons into the hands of even more of its proxies," he told reporters.
There was no immediate reaction from Iranian officials.