Even before any retaliation from Iran against the US for its killing of top general Qasem Soleimani, the backlash from the Trump administration's Middle East policy is clear, present and dangerous.

You can trace this new era of instability and the possibility of a new Middle East war to President Donald Trump's demand for a better nuclear deal with Iran, one that sought to curb its regional power, and severe sanctions to speed up regime change.

Since he pulled the US out of the Joint Comprehensive Plan of Action (JCPOA) nuclear deal in May 2018, Iran's stance as a regional player has been unchanged -- Bashar al-Assad's victory in the Syrian war is an example of that.

And in response to Soleimani's death on Friday morning, Tehran has taken major steps back from the 2015 nuclear deal, which at least curbed its uranium enrichment and nuclear ambitions.

As for regime change, the mass public turnout in Iran and around the region to mourn Soleimani should not be underestimated. Even those in his own country who had no love for him -- or their Islamic Republic -- are now bound again by patriotism and nationalist fervor.

Read the rest of Amanpour's analysis here.