There is no US empire

The US does not have what past true empires had.

If we look at past empires, like the Persian, Greek, Roman, Mongol, Ottoman and British, what distinguished them was that the principal nation actually administratively and militarily controlled their territory. Conversely, those empires collapsed once those territories were lost to them, either by internal resistance or other empires, or negotiated independence. So the last trues empires were probably the British Empire and the Russian-controlled USSR.

Unlike the true empires, while the US has had some territories, it has mainly relied on military reach through bases in independent countries aligned with them. Thus they lacked the true administrative and military control of them that true empires in the past have had. While the US has had a huge cultural reach, which has largely undermined and supplanted a lot of the populations' thinking in a lot of countries, the only times when the US exerted military pressure was to overthrow governments that actively opposed US companies.

This lack of the US having long experience of administering vast foreign territories and having to adjust to managing millions of local inhabitants explains why it has been notoriously incompetent at re-establishing functioning administrations in countries it has been in wars with since the Marshall Plan after WWII. The US has been more interested in dominance by proxy through dictators. Actually controlling countries requires developing the deep and broad logistical supply lines to manage the resource extraction that having the territory affords.

With Trump and Iran, we are seeing the true paper tiger that the US forces are because they cannot maintain a military manufacturing supply line for themselves enough to actually resist a sustained asymmetric warfare against low-cost weapons. The US have had to back down so often because they did not have the military capability to enforce what their bases in the Middle East projected. Now the US influence is being challenged on so many fronts in economic and cultural battles of their own making. The so-called US empire is a fraud.

Iran, as did Vietnam and Afghanistan, shows that the US does not understand why populations resist conquering, and that is because it has never conquered a peoples that it then had to maintain control over for an extended time. It had a doctrine of hearts and minds, but that is very shallow compared to the level of infiltration needed for long-term population control. Empires survived because they learned the governing skills. The US never has. Short-term overwhelm is not governing. Only those who have endured through waves of long-term occupation can know what resistance is.

Empires have arisen out of the deep lessons leaned from being dominated and applied them to their own conquered territories. They have spawned each other in cycles of repression and conquering, only to be conquered by others or collapse under their own bureaucracy. The US was not foundered by a conquered peoples, but by the disparate remnants of those who sought refuge from their former societies. That is not the same depth of resistance that builds an empire, but it is enough to use myths to tell itself that it is.