[Suhiir]

The USMC has always been "Light Infantry", just with heavy supporting assets in terms of helos/air. And when near the coast the fire support of whatever the US Navy has nearby.

They typically operate as quasi-autonomous mini-brigades built around an infantry battalion with a battery of artillery, a platoon of tanks, and a composite squadron of attack, observation, and transport helos and if truly operating independently a composite squadron of fixed wing aircraft. The big thing is they're highly mobile and much faster to mobilize then most US Army formations, and have built-in logistic and maintenance assets and typically carry apx. 90-days worth of supplies.

Certainly not "heavy" enough to take on fully armored/mech opposition offensively (they do OK defensively) but pretty competent vs most anything else.