There are four intertwined reasons for President Donald Trump's late-night, 276-character Twitter warning of war with Iran: "NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES."
First, the Trump administration is effectively pursuing a policy of regime change in the Islamic republic, hoping expanding sanctions will break the Iranian economy. Hours before Trump's blast, Secretary of State Mike Pompeo gave a high-profile speech in California, proclaiming US support for protests against "hypocritical holy men."
Second, Iran's regime -- the Supreme Leader and President Hassan Rouhani, forced into tougher rhetoric by hardliners -- are issuing their own threat: to hinder the oil exports of other countries if Tehran's sales are sharply reduced by US sanctions. That threat could include blocking the Strait of Hormuz at the top of the Gulf, a vital route for oil tankers.
Third, Trump's ego was poked by Rouhani's direct address in a speech Sunday: "Mr Trump! We are the people of dignity and guarantor of security of the waterway of the region throughout history. Don't play with the lion's tail; you will regret it."
And fourth, Trump needs a distraction from the fallout over his Helsinki summit with Russian leader Vladimir Putin and -- more importantly -- the Trump-Russia investigation that is closing in on him.
In the past 10 days, 12 Russian military intelligence officials have been indicted, the smoke from Trump's former lawyer Michael Cohen cooperating with Special Counsel Robert Mueller is rising, a declassified document has highlighted suspicions of Russian coordination not only with Carter Page but with other Trump campaign advisors, and the trial of former Trump campaign manager Paul Manafort is looming.
But is there a fifth reason for Trump's all-caps blast? Could this be a maneuver -- as with North Korea over the past 18 months -- to threaten war, only to pursue a flashbulb-popping photo op with Iran's leaders?
Even assuming that Trump's tweet was based on rationality, rather than regime change hopes or personal animosity, there are a series of barriers to any sudden Trumpian mission to Tehran.
Regime change means no talks and no resurrection of the July 2015 nuclear deal. Trump's top advisors, Pompeo and National Security Advisor John Bolton, are devotees of the toppling of the Islamic Republic's leaders. Trump's close friend and personal attorney Rudy Giuliani was in Paris last month headlining a conference of the National Council of Resistance of Iran, which has pursued violent as well as non-violent overthrow of the Iranian regime since the 1979 revolution.
Unsurprisingly, Iran's Supreme Leader is not an advocate of regime change. And, even if Trump's team foresees talks based on Ayatollah Khamenei taking a knee, the cleric will never accept the terms. As he said on Saturday: "I have always been insisting that we cannot trust the words or even signatures of the US authorities. Hence, negotiating with the US is useless."
Through his vague but strident declaration of a resistance economy for self-sufficiency, Khamenei has put down his marker. He expects Iranians to sacrifice in defiance of the US. He is gambling that his will prevails over any nationwide protests: After all, he survived the mass demonstrations after Iran's disputed 2009 presidential election.
Iran's hardliners currently have the upper hand. Rouhani's tough talk, with a "mother of all wars" reference on Sunday, is a capitulation to factions such as the Revolutionary Guards as well as the Supreme Leader's office.
The President is blocked from any outreach to the US. He is even having to pull back from pursuit of links with the European Union, which is trying to salvage the nuclear deal but struggling to protect European companies against American punishment.
The recent experience with North Korea works against any prospect of Trump switching from regime change war-war to jaw-jaw with Iran. His vision of a historic deal with Kim Jong Un has quickly faded, with Pyongyang playing hardball over any substantive negotiations and stepping up rather than scrapping its nuclear program.
Trump may have sought last September to get a handshake and picture with Rouhani at the UN General Assembly. However, those days are long gone.
We are not talking a quick jump from Twitter war to real war. The Trump administration's preference is still for economic collapse in Tehran.
But the risk of military conflict is real -- from the provocation of tweets and speeches on both sides, from the takeover of wounded egos, from alpha-male miscalculations and from the fallout of a resistance economy that can no longer resist.