The U.S. Army is undergoing a rare restructuring. This one will cut the number of infantry or tank battalions per brigade from three to two, and add more support units. This allows brigades to be sent overseas without the last minute addition of a lot of support units (engineer, supply, transportation, signal, Etc.) from division, or higher level, units. That means the new brigades train all the time with the support units, because those support units are part of the brigade. Those support units will also get more realistic training, and more combat training as well.
This reorganization will increase the number of combat brigades from 33 to 43. This will provide enough brigades so that active duty brigades can spend at least two years at home for every year they are overseas. For reserve units, the goal is at least four years at home (not on active duty) for each year spent on active duty overseas. The army expects to make this work because of large reductions in the number of American troops in Iraq over the next two years. By the middle of 2006, the U.S. expects to have only 80,000 troops there, and as few as 40,000 by early 2007. This is being done as Iraqi police and army units take over security duties.
The last major army restructuring was in the early 1960s, when the current system of brigades and divisions was adopted. For a few years before that, there was a disastrous, and short-lived, reorganization for a hypothetical nuclear battlefield. These Pentomic divisions replaced the World War II era unit organizations. It was during World War II that U.S. Army organization finally got modernized. The organization adopted for armor divisions back then (brigades and a variable number of battalions), was the basis of the 1960s reorganization, and is still at the core of the new brigade organization.