The Army fell short of its recruiting goal for May, its first significant slip in two years.
The active-duty Navy, Marine Corps and Air Force services met or surpassed their May targets; the Army National Guard and Air National Guard fell far short.
With an array of special incentives for attracting recruits, the Army managed to recover from a 2005 recruiting slump, but the impact of the Iraq war and the strong domestic economy have made it difficult to attract enlistees.
The Army and Marine Corps have recorded the most casualties in Iraq.
The pace of recruiting is even more important now that Defense Secretary Robert M. Gates has set a goal of increasing the size of the active-duty Army by 65,000 to a total of 547,000 within five years. The increase is intended to ease some of the strain on the Army from its heavy commitments in both Iraq and Afghanistan.
The Marine Corps also is expanding, although by a small amount.
Statistics released yesterday showed that in May the Army signed up 5,101 recruits, short of its goal of 5,500, although it remains on track to meet its goal of 80,000 for the year, which runs from Oct. 1, 2006 to Sept. 30, 2007.
"May is historically a difficult month to recruit," said Maj. Anne Edgecomb, an Army spokeswoman. High school graduation and other spring events tend to make it harder to attract the attention of potential recruits.
The Army tends to have its best recruiting months during the summer.
The last time the active-duty Army missed a monthly goal was September 2006, although that was a special circumstance: The Army already had met its full-year goal by September, so it chose to defer some sign-ups to later months.
In 2005 the Army missed its recruiting target by wide margins four straight months, through May. But it began a recovery that continued until last month, propelled by bigger enlistment bonuses and other incentives.
The Marine Corps had a banner month in May, signing up 2,225 recruits compared with its goal of 1,665. The Navy hit exactly its target of 2,709, and the Air Force met its goal of 2,451.
The Army National Guard met only 88 percent of its goal and the Air National Guard met 77 percent of its goal.