The US clearly hasn't always been aggressively expansionist. It isn't today.
America has had the most powerful military on earth for 70 years, along with a large population. List all of the vast amounts of territory it has annexed using that extraordinary military power. There are endless opportunities to do so, and the US is the sole military with global projection.
Some people point to military bases. Which doesn't work in any regard. A few critical differences being: taxing power on the local population, or vast plunder. Neither of which America is known for. And US military bases around the globe overwhelmingly exist by permission.
But why bother to control territory unless one gets some benefit from it? Throughout history, nations have sought more territory because most wealth came from land and its use. Annexing territory was the fastest way to grow the tax base.
Controlling territory but not extracting wealth is pointless. The U.S. doesn't extract wealth from its foreign bases; in fact it injects wealth because the bases are paid for by U.S. dollars but the downstream spending goes into the local economy.
And you might think "well the U.S. extracts the wealth through trade." But trade is mutually beneficial (unlike taxes) and the U.S. runs a foreign trade deficit anyway.
The things that the U.S. gets for its projected power are peace and stability. These are things that benefit any nation, though.
America has had the most powerful military on earth for 70 years, along with a large population. List all of the vast amounts of territory it has annexed using that extraordinary military power. There are endless opportunities to do so, and the US is the sole military with global projection.
Some people point to military bases. Which doesn't work in any regard. A few critical differences being: taxing power on the local population, or vast plunder. Neither of which America is known for. And US military bases around the globe overwhelmingly exist by permission.