By John Lyons, ABC
US President Donald Trump has told protesters in Iran that help is on its way. Photo: MANDEL NGAN / AFP
There is now a strong likelihood that US President Donald Trump will order air strikes against Iran.
In some ways, Trump has backed himself into a corner, declaring defiantly that should the Iranian regime open fire on its own people, then the US would take action against the regime.
He's told protesters that help is on its way. What help? And when?
The regime has done exactly what Trump warned against. While an information blackout has made it difficult to assess the exact extent of the death toll, it is clear that hundreds, if not thousands, of Iranian protesters have been killed by the country's security forces.
So what are Trump's military options?
At this stage, the one that's most likely is air strikes on military bases and warehouses controlled by the Islamic Revolutionary Guard Corps (IRGC) and its civilian enforcers, the Basij militia.
The Basij will be a possible target for the US as they are vital in trying to put down these protests. The Basij are volunteers who answer to the IRGC. Many workplaces have Basij members - often their colleagues may not even know for sure that they are Basij, even if they have suspicions.
A member of the Basij receives many benefits - such as prized jobs or places in universities for which they would not otherwise have qualified.
But there is one condition: the IRGC can call upon them at any point to do whatever is required to "protect the Islamic Revolution".
Now is when the IRGC will be calling in those debts. They will be instructing the Basij to work their way through the various crowds and then to try to disperse them.
In 2009, I saw members of the Basij trying to break up crowds. They ride around on motorbikes, usually dressed in black and often with their faces covered by scarves to protect their identities.
I saw some with clubs who, without warning, would start bashing members of the crowd. Others carried machetes. They roam the streets like gangs, often 15 or 20 in one group.
Many of those protesting will know the fear that 15 or 20 Basij arriving at a scene can instil. The Basij can - and do - kill with impunity.
What the Basij will be worried about at the moment is whether the size of the crowds could mean that when they try to break up a protest there is a chance they'll be overpowered, despite being armed with bike chains, knives and machetes.
If this were to happen across the country, it would become a tipping point for the protesters.
This would be the point at which the regime may start to lose the streets.
Iran weakest it's been in years
The reason air strikes are the most likely option for the US is because at present, there is no US naval battle group near Iran - which means the US cannot, for the moment at least, use naval-based weapons. But it can quickly marshal significant air power from its various bases through the Middle East.
The Saudis and Emiratis, among others in the region, are nervous about the US launching a new attack on Iran - they fear the response that Iran may engage in.
But a major calculation of the Trump White House is that Iran is the weakest it has been for many years. Air strikes last year by Israel and later by the US have weakened the country.
Added to this is the fact that Iran's major proxy militia, Hezbollah, has been largely degraded by Israel. This means that Iran's ability to respond is limited. Israel and the US have made sure that Israel is largely protected against incoming missile attacks from Iran, as was shown last year.
Very few missiles fired by Iran were able to penetrate Israeli airspace, with many intercepted by Jordanian and other jets as they crossed the Middle East.
In the year since his return to the White House, Trump has settled upon his military option of choice: short, surgical operations that raise minimum danger for US forces.
Trump is eschewing the military strategies used by so many of his predecessors - so far, at least. He's decided not to deploy large numbers of US forces into foreign conflicts it may then take years to extract them from.
Under the Trump military doctrine, the quagmires of Iraq, Afghanistan and Vietnam are a thing of the past. As an instinctive politician with an extraordinarily sharp sense of the public mood, Trump knows Americans are fatigued from these sorts of conflicts.
Trump boosted by Maduro operation
The Trump White House, and Trump himself, are clearly pumped by the recent successful extraction of Venezuelan President Nicolas Maduro.
History will judge it as one of the most extraordinary military operations of modern times. US intelligence had spent months studying the daily habits of Maduro and his family. As US defence officials have said, the Pentagon in Washington knew Maduro's daily routines, what he liked to eat and even the behaviour of his pets.
-ABC
