The Department of Defense believes that the rapid victories in Afghanistan and Iraq proved that choosing the best weapons and equipment for the United States, not a particular service, was what made the difference. For over a decade, the Department of Defense has been pushing this concept, referred to as "jointness" or "thinking purple." Senior general and admirals have been persuaded to cooperate with the other services in ways never before seen. This included using a navy aircraft carrier to move an army division or serve as a floating airbase for commandoes. During the Afghanistan war, the air force and navy cooperated in how they used their aircraft to assist army troops on the ground, with the guys on the ground calling the shots.
During World War II, this cooperation was the norm. Wars tend to bring everyone together. But five decades after the war, the services drifted apart. Actually, the World War II cooperation was misleading, because during that war the army and navy pretty much fought their own wars. It took several decades for everyone in the Pentagon to agree that cooperation was the way to go. But now getting everyone to agree that the money should be divided up with the same spirit of cooperation looms as a major problem.
Most people don't realize it, but new weapons and equipment are bought by the various services without much thought to how the money might be better spent on something another service needs. For over two centuries, the services (first just the army and navy, and since 1947, the air force as well) wheeled and dealed to get a chunk of money from Congress, then went on spent it on what they felt they needed to do what they thought they would have to do in the defense of the country. Now, for the first time, it's being proposed that defense spending be scrutinized in terms of how it contributes to the overall defense of the nation. This will be very difficult. Not so much because each of the services has its own agenda, but because each major weapons system or spending program has patrons in Congress. All that money is spent in someones electoral district, and the voters get angry if the spending goes away. Well, maybe the voters don't even notice, but an opponent in the next election will notice and make an issue of the lost defense money.
There are several obstacles. The main one is that each service has a quite different view of how wars are fought. The army believes that everyone else is there to basically help the infantry defeat the enemy so that the grunts can occupy the foe's cities. The navy believes that in many situations there is no need for the army and air force. Most American wars are "little wars" and the navy (along with its marines) sees itself as quite capable of taking care of most of these by itself (with the army and air force coming in later for long term occupation, if needed.) The air force sees itself as the weapon of the future, able to bomb the enemy into submission, leaving it to the army to come in and round up prisoners and perform occupation duty. The air force feels that it's long range bombers can do anything the navy can, although the fleet is still useful for protecting merchant shipping against hostile subs.
These three different views of warfare produce demands from each service for a disproportionate share of the defense budget. But military historians and wargamers in the Pentagon have developed a more balanced view that is now threatening some very expensive weapons projects (new warplanes like the F-22, new warship designs and new army combat vehicles and helicopters.) The major problem here is that Congress, and defense industry lobbyists can be very effective in defending the existing projects, and proposing new ones that certain companies want to produce, but no one in the Pentagon really wants. This is the "military-industrial complex" that President Eisenhower warned about back in the 1950s. One thing Eisenhower (a former general) missed was the increasing interest of Congress in protecting projects. Congress is responsible for approving the president's budget proposals, but defense industries have long since learned that if the spending is spread among enough of the right Congressional districts, the legislators will get behind the project, whether the Pentagon really wants it or not.
The Pentagon, taking advantage of procurement common sense that tends to exist only in war time, is trying to make fundamental changes in how defense budgets are made up. But a lot of sacred cows are at risk, and the spin machines will be running a full speed as everyone tries to protect their favorite projects. There will be much talk of "what's best for the troops." A lot of that talk will be self-serving lies. It could get interesting.