Trump in May pulled the United States out of the 2015 Iran nuclear agreement struck by the Obama administration by calling it the "the worst" deal ever negotiated.
Trump tweeted Sunday if Iran threatened the U.S., it would "suffer consequences".
What we don't know is how Iran will react to such harsh rhetoric, or if Trump is playing at a risky game by trying to distract from the Russian Federation kerfuffle by creating a Twitter dust-up with another adversary.
Later that day, Iran President Hassan Rouhani threatened the United States, saying "war with Iran is the mother of all wars".
Limbert was among those held captive at the U.S. Embassy in Tehran during the 1979-1981 Iran hostage crisis, and more recently advised the Obama administration.
In May, Trump - who has made Iran his public enemy number one - announced the USA withdrawal from what he called a "defective" multinational nuclear deal with Tehran, and moved to reinstate punishing sanctions.
"To Iranian President Rouhani: NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE".
Iran, as a result of his decision, is not the same country any more, he asserted.
Hilarious send-ups of Donald Trump's extraordinary Iran rant
Mara also noted that Trump also directed violent language toward North Korea - before meeting with Kim Jong Un in Singapore. Norths Foreign Ministry accused the United States of making "gangster-like" demands for its unilateral disarmament.
In the case of North Korea, the verbal war cooled quickly and gradually led to the high-profile summit and denuclearization talks.
"We've been around for millennia & seen fall of empires, [including] our own, which lasted more than the life of some countries". He's trying to show Iranians that the Trump administration backs those opposing the Iranian leadership.
After speaking with European officials about Trump's warnings, International Crisis Group president Rob Malley said diplomats on the continent were not "really taking it seriously".
Several observers noted the similarities between the threats on Iran, and Trump's "maximum pressure" campaign towards Pyongyang.
Trump's tweet doesn't appear to have been prompted by any notable shift in rhetoric from Iran. Analysts say activists inside Iran see a connection between the worldwide tensions and the worsening economics.
"One council member has moved away from the deal", Skoog said of the Trump administration's withdrawal from the 2015 agreement, "so of course that makes it hard for the Council to express itself, but the great majority of Council members and certainly members of the United Nations are fully behind the dealthat was struck".
He said that the US Broadcasting Board of Governors was going to attempt to circumvent Internet censorship in Iran by creating a slew of Farsi media outlets (including television, radio, digital and social media) to show "ordinary Iranians inside Iran and around the globe [that] America stands with them".