Weather wreaks havoc with the battlefield, as do other enviromental elements - disease and pests.
Sometimes, the battle theater itself is an impediment ... diffcult terrain, incompatible transportation and energy systems.
Other times, it's politics - Turkey wouldn't allow US troops to invade Iraq from its territory in 2003; Spain wouldn't allow US bombers to fly over its airspace during the 1980's Gulf of Sidra conflict with Libya.
The civilian economy may not be able to provide sufficient, rapid re-supply of munitions and equipment for a prolonged conflict.
Civillian inhabitants of a battle theater may be hostile.
The United States lacks the industrial infrastructure, capabilities, and capacity that won the Spanish-American War, World War i, World War II, the Cold War, and the First Gulf War.
To rebuild American capacity to make war, the Pentagon also needs to keep tabs of the re-industrialization of the American economy and the re-shoring of supply chains.
Foreign adversaries could start an economic war without firing a shot by no longer purchasing US Debt. This would increase interest rates, cause a liquidity freeze, a seizure of credit markets, reduced economic activity, and political instability.
War is military, economic, technological, political, and social.
The American military's biggest vulnerabilities are economic, political, and social - outside the direct control of the Pentagon.
America's public institutions (social, political) are dysfunctional and private business maximizes profit by offshoring strategic industries to China.
Good luck wargaming a non-functional Congress and enemy ownership of America's debt and supply chain.