The Army has the green light to grow by tens of thousands. Now comes the hard part: recruiting, training, equipping and paying for all those new soldiers.

Defense Secretary Robert Gates' plan to permanently add more than 35,000 soldiers over the next five years presents a new set of challenges to juggle along with surging ground forces into Iraq, rebuilding equipment battle losses and upgrading soldiers' living quarters in the United States.

President Bush plans to send 21,500 additional troops to Iraq in the coming weeks in an attempt to quell violence in Baghdad.

The right size for the Army — by far the largest of the services — has been debated since the drawdown of the late 1980s and the 1990s, when the force was slashed from 780,000 to 480,000 troops.

Retired generals, lawmakers and military experts differ on the subject as the Army struggles to deploy soldiers to Afghanistan and Iraq and still remain ready to face future threats.

The Army has been simultaneously building a future force and increasing the current active force from 33 to 48 brigade combat teams.

Four years ago, Congress authorized the Army to temporarily increase its 482,000-soldier end strength by 30,000 through 2011.

The Army will reach the 512,000 goal "by the end of this year," Gen. Richard Cody, vice chief of staff, said on Jan. 10, the day Bush announced the troop surge.

Gates wants to make the 30,000-soldier increase permanent.

On top of that, he has authorized the Army to grow by another 7,000 soldiers a year, boosting its total end strength to 547,000 soldiers.

To make that happen, the service will have to beef up its force of recruiters and trainers, said Gen. William Wallace, commander of Army Training and Doctrine Command.

"An increasing Army will need an increased capability within the institution to do the recruiting, the training and the leader development that we are directly involved with," Wallace said.

Gates also announced he intends to add 27,000 Marines over the next five years.

This will raise the competition for recruiting young people suitable for service.

Wallace pointed out the difficulties recruiters face in trying to enlist enough young men and women to meet the Army's ambitious growth plans.

Of all those individuals between the ages of 17 and 24, "73 percent of them are not qualified to enter the Army," Wallace said.

Out of a potential 32.4 million young people in this age range, only 1.2 million meet the intellectual, moral and physical criteria to serve in the Army, Wallace said.

Still, Cody said, an impressive number of young people are coming forward to serve their country.

"This war is absolutely a story about a generation who has been flooded on TV about the horrors of this war and about how dangerous this world is, and they have stepped forward and said, 'America, in your time of need, I'll defend you.'

"And no one thought this generation would do that," Cody said.