As American forces assemble in the Persian Gulf for a possible invasion of Iraq, they are being reminded of an old problem; the inability of the different services to train together in peace time for operations like this. The problem was noted during the 1991 Gulf War (and several smaller operations in the 1980s), but little was done. The easiest solution is to give the regional commanders authority to train units from different services in peacetime. The different services won't go along with this, pointing out that they don't even have enough time, or money, to train their units for their primary functions. Every time an armored division, navy task force or air force wing goes out and training, it costs millions of dollars and weeks of time. In peacetime, troops spend most of their time either maintaining their equipment, learning how to use it (or new versions of it) or training with it. Adding a new category, "training with other services" would take time and money from existing activities. But the fact remains that, in war time, the units from the army, air force and navy have to learn, on the spot, how to work together. Knowing that this does not always work out very well, the Pentagon has been running more wargames and urging the services to get to know better how the other services operate. Meanwhile, every operation involving two or more services is guaranteed to produce some unexpected misunderstandings and incompatibilities between the troops who haven't trained together.