Actually, you do. You first put pressure on them to see their reaction. If you see no reaction, you will progressively increase pressure on them and entrench them. A game changing move is a move that leads to them recalculating their strategy. As long as they see no such move, they will continue to entrench Iran militarily, economically and politically.
Again, while taking these steps you are still pursuing a concrete objective. And entrenching Iran wasn't that objective per se, forcing Iran to the negotiating table to make further concessions was. In particular to limit its ballistic missile arsenal and to draw down its presence in the region.
This much was explicitly stated by the Trump regime.
Their strategy failed to reach its objectives. The Trump regime did not alter this strategy because it was stuck with this unproductive method (back-pedalling was not really an option Trump was willing to choose since it would make him lose face).
As I said, the US is pretty happy with the status quo. Why shouldn't they be? They have isolated Iran with minimal cost.
Islamic Iran has always been more or less isolated from the zio-American sphere of influence.
Yet its allies are still there, standing strong, putting up resistance and being more numerous than before (given the addition of Yemen's Ansarallah).
Their attempts to suppress Lebanese Hezbollah (or to extract it from the Iranian orbit) haven't yielded any results. Nor has their attempted "colored revolution" or rather, "colored social movement" in Iraq succeeded in neutralizing Iran's interests there. Same goes for their efforts to eject Iran from Syria and to drive wedges between Damascus and Tehran. Their scheming to make Hamas cut ties with Iran hasn't led anywhere either.
Iran's missile program and other defence sectors have been experiencing unabated progress and expansion.
Their end goal is not to keep Iran isolated and under pressure. It is to destroy and dismantle Iran. To achieve that, they need Iran to abandon its missiles and to be unable to rely on this many idelogically-motivated allies accross the region. This is the standard by which their success or failure ought to be measured.
If you look at the game from Trump's perspective as a tactic to show him triumph and strong in the eye of the public, you can say that Trump's maximum pressure campaign failed miserably. If you look at it from the perspective of the US as a system, the very fact that you and I are now discussing the issue of returning to the JCPOA shows that their maximum pressure campaign has worked. So, one can say that Trump's maximum pressure campaign worked and the next US administration is going to inherit a leverage in the next negotiation, if there will be one.
The US as a system needs Iran to be obliterated from ground up. I don't see any groundbreaking progress in that direction.
We will always be discussing plots by the zio-American empire against Iran. They are not going to stop scheming and Iran is not going to stop resisting.
And as you noticed, I expressed the view that they won't manage to have Iran acquiesce to additional concessions in exchange for a return of the US to the JCPOA. If it goes as I predict, there will be no win for Washington. Furthermore, you concur that another negotiation anytime soon is uncertain to take place or to bear fruit.
I don't know to be honest. Decisions like this are made by the system, not only one person. Everyone knows that I hate Rouhani with a passion, but I don't think he is solely responsible for the JCPOA scandal. Khamenei gave him the green light and allowed him to stay in power for 8 years.
Because Rohani had enough political clout and influence within the system to pressure the Leader and make it hard for him to choose otherwise, and because circumstances favored the liberals at that point in time. These parameters no longer apply.