As President Trump wrapped up his first foreign trip on Friday, Iranian leaders made another defiant declaration in the war of words unfolding between Tehran and Washington.

According to a senior Revolutionary Guard commander who spoke to the semi-official Fars news agency, the regime has apparently built a third underground missile factory despite sanction by both the U.S. and the United Nations.

"Iran's third underground factory has been built by the Guards in recent years," Amirali Hajizadeh, head of the Guard’s airspace division, was quoted as saying. He added that the regime "will continue to further develop our missile capabilities forcefully."

The announcement flies in the face of a series of statements and sanctions designed to curtail this exact kind of activity. A 2015 U.N. Security Council resolution "calls upon Iran not to undertake any activity related to ballistic missiles designed to be capable of delivering nuclear weapons, including launches using such ballistic missile technology."

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The Trump administration imposed new sanctions in February of this year in response to an Iranian missile launch shortly after the president's inauguration. The sanctions came after President Trump declared on Twitter that he was formally putting Iran "on notice."

It was barely a week before Iran was conducting tests again, even launching the new missile from the same launch pad used a week before.

Tehran was back at it about a month later, launching a pair of ballistic missiles in a test that unfolded around the same time as an alarming confrontation between Iranian fast-attack vessels and a group of U.S. Navy and international warships.

Just last week, the administration announced a new round of economic penalties over activities related to Iran's ballistic activities and programs. And President Trump has made a point to criticize Iran publicly, and repeatedly, during his ongoing trip to the Middle East and beyond.

IRAN'S ROUHANI: WE WILL NOT WAIT FOR US'S PERMISSION TO TEST BALLISTIC MISSILES

The president has called out the regime by name, suggesting that combating "the threat posed by Iran" is a top priority, and blaming Tehran for the spread of "destruction and chaos" across the region.

On Saturday, Secretary of State Rex Tillerson said he hoped Iranian President Hassan Rouhani, who had just been re-elected for a four-year term, "puts an end" to the launches.

Just a few days later, on Monday of this week, Rouhani made clear that won't be happening anytime soon. Iran's missiles "are for peace, not for attack," he said, adding that his nation will not wait for "permission" from the U.S. and others before conducting its own controversial tests.