No self-respecting government, like Iran or North Korea, will negotiate while the US is imposing sanctions on them, ie while the US is waging economic war on them. And of course, the US knows this and that's why it won't lift the sanctions. The US was never interested in diplomacy, only in regime change. It has wanted this for 40 years, since the overthrow of the pro-western Shah of Iran in 1979. Its goal is to force regime change and install a puppet government in Iran that will kowtow to US interests. The US is hoping that sanctions will destabilize Iran's economy to the point where the citizenry revolts and forces regime change. I doubt this will happen - the Iranians are tough - but I think all out war is even less likely. The US always tries to make the other side look like the bad guy, in order to manufacture public consent for it's actions. It doesn't want to look like the cowardly schoolyard bully who beats up and steals the lunch money from smaller kids, although that's a pretty good analogy. Iran's leaders refer to the US as 'The Great Satan" for good reason.

And so, while the Trump show entertains and distracts the public, others forces are covertly engaged in a regime change operation against Iran, which is in the early stages of a predictable pattern. First, destabilize Iran's economy and government through sanctions and covert CIA operations to create civil unrest. Second, send in rebel forces (ISIS) and try to instigate rebellion in the Iranian military. Third, when Iran's government fights back against the rebels, demonize the government as evil dictators, monsters, terrorists who are building a nuke, etc, who are starving, bombing, gassing, etc, their own people and/or the people of neighboring countries. As an added touch, the US may orchestrate false flag attacks against Iranian civilians or US assets, which it will blame on the government. Fourth, send in limited US and allied military forces to complete the regime change under the guise of liberating the Iranian people from their oppressive government. The US used this 'template' in Syria and Venezuela, but Russia stopped both coup attempts, which is partly why the US demonizes Russia so much.

The US has been quietly rebuilding its proxy army, ISIS, in Afghanistan and Iraq where 'coincidentally' it has maintained bases since its regime-changing invasion of these countries. Afghanistan is on Iran's eastern border, and Iraq is on its western border. I'm pretty sure the US is using the bases to provide ISIS with training and logistics support and it may turn ISIS loose in Iran as it did in Syria. I don't think Russia has strong ties with Iran like it did with Syria and Venezuela, so it's questionable if it will intervene. As Trump likes to say, "We'll see what happens."