For the last two decades, the United States has reorganized it's armed forces so that the reserves (which include the National Guard) contained a larger proportion of support units (partially because many reservists do the same kind of work in their civilian jobs) and a larger proportion of combat units (which benefit from more battle drill than reservists can get.) Today, the army reserves are actually larger (564,000 troops) than the regular forces (479,000.) The increasing number of peacekeeping missions has called for more support units, and more reservists have been called to active duty as a result. In the first four years of the Bosnia operation, more reservists were called up than during the entire Vietnam war. To put it in more stark perspective, during the late 1980s, reservists spent less than a million man days on active duty. In 1999, reservists spent 13 million days on active duty.