The enemy gets a vote on how short or long a war is.
[Unless you are talking about a nuclear first strike by America, resulting in global Armageddon.]
And if the enemy has already ramped up military weapons and ordnance production, they can last longer than a country that has not. Witness Russia/Ukraine.
Our own American military analysts have made painstakingly clear we are not currently able to fight a “near-peer” fighting force and it will be years before we can for many reasons and the draw down of weapons is only a part.
Britain came out yesterday and said because they had depleated much of their weapons (which many called an “excuse”) to Ukraine it will be 5 to 10 years before they can raise a division to fight along side the U.S.