Who expected Donald Trump to propose a summit meeting with the Iranian president? Practically no one but perhaps they should have, because it follows the Trump playbook. He threatened "fire and fury" against the North Korean leader, Kim Jong-un, and they ended up shaking hands in Singapore. Last month he threatened Iran with "consequences the likes of which few throughout history have ever suffered", so perhaps the show could be repeated.
Actually, the two situations are not similar. Mr Kim was already in possession of the technology and material to build a nuclear weapon. He has an ally in the form of China which will ensure that his regime survives and it provides a model of transition from communism to consumer-based capitalism.
As for Iran, it is in a more lonely position. While China and Russia are in principle opposed to the United States undermining the Iranian government, it is not clear how far they would go to prop up the mullahs. Nor does Iran have a workable nuclear weapon – yet. The path to reforming its clerical regime is unclear, to say the least.
This has put Iran in a bind: the offer of a summit is seen in Tehran as an attempt to divide the people from the regime, at a time of acute economic hardship caused by the collapse in the value of the rial and with further pressure coming in November when the US will step up sanctions on oil exports.
So Tehran has been careful to avoid ruling out any direct talks with the US so as not to appear intransigent. It might have to do this at some stage, although not necessarily in the form of a summit meeting, if the sanctions have the bite that Mr Trump expects.
On a personal level, Mr Trump believes he has the ability to achieve a better deal than the agreement pulled off by his predecessor, Barack Obama, which suspended Iran’s nuclear programme. Given that he is also in summit mode, having spent almost two hours in private conversations with the Russian president, Vladimir Putin, he is no doubt looking for a much broader arrangement.
We do not know what the two presidents discussed in Helsinki on July 16 but it is a fair bet that they discussed if not a grand bargain involving Syria, then something close to it.
Mr Trump has said he wants to withdraw US troops from Syria once ISIS is crushed, unless the troops are required to limit the influence of Iran. ISIS has lost most of its territory so the question of US withdrawal – and the future of Iran's troops and proxies – is rising up the agenda.
One option would be the removal of all foreign troops from Syria – the Iranians and the Americans – with the Russians staying behind as trainers or advisers. Russia has clearly stated that its goal is the eventual removal of all foreign troops from Syria, to the discomfort of Iran.
The Russian ambassador to Israel, Anatoly Viktorov, said on Monday that Moscow did not have the power to tell the Iranians to go home. The Iranians were “playing a very important role” in driving out terrorists in Syria, he added, so it was unrealistic to demand the expulsion of foreign troops “for this period of time”.
The question is, how long is “this period of time”? Thanks to Russia’s phased plan of picking off rebel strongholds with ferocious air assaults, the regime is regaining territory every week.
The big question is when the assault will begin on Idlib province, where the remnants of the rebels are kettled.
Even if victory is not complete, the regime is behaving as if it was. It has begun issuing death certificates for some of those who disappeared in Assad’s jails, as if to say: “We’re back in charge. This is the future.”
Would Mr Putin accept a deal under which the US withdrew its forces from Syria and accepted that Russia was in control there, provided the Iranian forces also withdrew? The carrot for Mr Putin is that an Iranian withdrawal might ease Arab opposition to accepting the bitter reality that Bashar Al Assad remains president, at least for now.
There are a couple of reason why Mr Putin might not think this is a good deal. The Americans will probably quit Syria in any case – so why give them a big prize? Mr Putin can see that the tide of western hostility to Russia for its ruthless support for the Assad regime is turning: last month French President Emmanuel Macron gave his blessing to the Russian military by sending a planeload of humanitarian supplies for the army to distribute in Syria.
The second reason is that Mr Putin has experience of Washington’s transactional way of dealing with him. They have been several attempts to “reset” relations. An outstanding problem is solved, everyone shakes hands and the Americans go back to treating Russia as an irritating minor power.
Another such reset will not be enough. He will not want to be seen so transparently to be doing America’s bidding in Syria. His gambit in intervening to rescue the Assad regime is, in his eyes, the foundation of Russia’s long-term influence in the Middle East, not a quick in-and-out manoeuvre.
Patient Russian diplomacy and the effective use of air power have enabled Russia to achieve its goals in Syria while managing the competing interests of regional powers Iran, Turkey and Israel. By contrast, the US cannot even secure the freedom of an American pastor who has been detained by its ally Turkey.
And if there were to be a grand bargain, it should extend far beyond Syria. Mr Putin would want the US to recognise Russian interests in its immediate neighbourhood – such as Ukraine – just as America for years asserted primary domain in its own hemisphere.
For Mr Trump, that may look like the art of the deal in action. But for Congress and the US foreign policy establishment, that would be a poison pill to swallow.
Alan Philps is editor of The World Today magazine of international affairs