Regime change is hard. If you don’t believe it, just ask the people of Iran and Venezuela.
There are significant similarities between the two. In both instances, Trump has applied the maximum possible economic pressure. In both cases, he appears to expect and want a negotiated solution, albeit one that gives him everything he wants. In neither case has it worked; the result has been widespread misery, but no progress. And in both situations, the regime has retaliated, but not to the point of provoking war.
There are differences, too. Trump’s emotional investment in Venezuela is more limited. America has more diplomatic support on Venezuela than on Iran. The Venezuelan regime is far less competent than the Iranian government. Finally, Iran is close to getting a nuclear weapon, and abuts the world’s economic lifeline. The dangers inherent in an Iran war are consequently much higher.
At this point, neither Trump nor the Iranians have succeeded in accomplishing their objectives. An impasse, however, cannot last forever. The Iranian government is not going to collapse without a military push. The ultimate choice for Trump will be war or an embarrassing failure.