Trump is
threatening Supreme Leader Khamenei with "a good time" and he doesn't even know it.
The
tragedy, if not
irony of Trump's death threat against Khamenei is that from the perspective of a Shiite cleric who possesses deep faith in the prevailing monotheistic god of Abrahamic religious traditions, and who has devoted most of his life to serving said god — which some of us may refer to as Allah, even though Muslims have 99 names for Him — there is no honor greater or end nobler than martyrdom.
The US will need months, if not a year+, as well as the activation of reservists to stage a "proper" ground invasion of Iran.
Someone has probably also convinced Trump that a significant deployment of ground troops will be unnecessary for subduing Iran, as that's exactly something Trump will want to hear before granting buy-in for a hot war against Iran.
We are
not going to see multiple BCTs and MEUs blitzkrieg into Iran, at least not this turn, especially as there
currently isn't even an American ally in the neighborhood that will let hundreds of thousands of American troops and contractors assemble on their territory to stage such a theoretical ground invasion.
What Trump is most likely hoping for is something akin to the air war NATO waged against Serbia in 1999 that more or less formalized the independence of Kosovo, and toppled the Milosevic government resulting in his subsequent extradition to the Hague; or the 2011 conflict where domestic rebels aided by Western air strikes and SOF removed Gaddafi from power, and which also sent the country into a civil war and anarchy that it has yet to recover from.
TBF, we probably should acknowledge that there is a significant chance that a limited number of US military personnel — operating under non-official cover and perhaps even posing as third country nationals — are already conducting what are known as advanced force operations inside Iran. Talking guys and girls managed by programs like DASR, so units and operations rarely, if at all explicitly acknowledged during public discourse.
Though depending on the targets that CENTCOM will want to prioritize kinetic effects against, the US might be able to fully or partially rely on Israeli operatives and assets — who are generally considered more experienced than their American counterparts at running operations in certain denied areas like Iran — for AFO missions out there, much of which will likely be CTR for triggering kinetic strikes assuming the upcoming party stays air centric.
Lastly, there is a not insignificant chance that certain units from JSOC or even "white SOF" elements like the 5th and 10th SFGs' Critical Threats Advisory Companies — which are known for developing specialized capabilities like breeching and raiding UGFs — will conduct direct action operations against Iranian ground targets of the highest priority.