WASHINGTON — The US Army chief of staff is looking at how the service might quickly regenerate the force when needed at a time when it is rapidly reducing its size.

The Army has already shrunk the force by 80,000 troops since withdrawing from Iraq in 2011, and it plans to further reduce its end strength in the coming years. The service is scheduled to reach an end strength of 450,000 troops by the end of fiscal 2017. If the Army continues to get hit with budget cuts, it could see a deeper cut down to 420,000.

On Monday at a Center for a New American Security conference in Washington, Gen. Mark Milley took pains to dispel the myth that it's easy to regenerate an Army.

"So there are a lot of myths out there about the size of the force, training the force, that you can bring an Army down very, very small and then in a time of crisis, add water, circle the wagons there, and stir it up and we'll have an Army," Milley said. "It's not quite that simple."

For instance, units can take three to four years to reach the standard level of combat readiness, according to Milley.

The chief said he'd prefer to keep as many troops as possible for as long as he is able, but reductions are moving forward. Therefore, he's left to think about how the Army might be able to more effectively build up the force if necessary.

To do that, Milley said: "I'm going to lean heavily on the [US Army National Guard]."

The Army, he said, is the only service with 50 percent of its capabilities in the reserve component, "so what I need to do is not only maintain the readiness in the regular Army ... but I've got to increase the readiness of the National Guard."

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If the active force is a certain size, according to Milley, it will most likely get consumed "pretty quickly" in any larger contingencies. "So we have to lean on the Guard," he said, "but that means I have to get the readiness levels up to a level that is combat capable."

It takes 100 to 120 days to mobilize a Guard unit, he noted.

The service has kept its policy of requiring 39 annual days of training for guardsmen since 1915, Milley said.

"It's a century old and I sit there and I go, 'What is so magic about 39 days?' Maybe we need to look at changing that," he said.

One of the options Milley is examining is increasing the number of training days for some — not all — guardsmen to 60 or even 100 days a year "so it reduces the response time on the back end."

Quick mobilization is becoming more and more critical given the speed of communication and the technology available today, Milley said.

"I suspect that any future conflict will unfold more rapidly than it has in the past," he said.

The US Army National Guard director said last month that he planned to deliver in the coming weeks recommendations to Milley on maintaining Guard readiness and training that better fits with a 21st century Army force.

The Army is also exploring a concept to round out brigades using National Guard troops, which worked well in the past, but Milley is considering taking that a step further where active troops would round out a Guard unit.

"I don't foresee any problem with an active unit — battalion or brigade — say, being a part of the 28th Division Pennsylvania Guard and they wear that patch," he said.

Milley said the Army continues to examine the effective partnership programs with the Guard and foreign countries along with a wide variety of other initiatives.

The partnership program is proving vital for the US Army as it looks to strengthen its support to countries in Eastern Europe that are nervous about Russia's aggression in the region. The National Guard Bureau chief and the US Army Europe commander have both said the Guard could play an important role in Eastern Europe in the coming years and are looking at how to grow that role.

Milley's laser focus to ensure the Guard's readiness and capability is maintained in equal measure is likely seen as encouraging to those in the National Guard who have been fighting some decisions the Army has made in recent years to reduce the Guard's end strength and take away some of its equipment.

At the center of the skirmish is the tug of war over the AH-64 Apache attack helicopter. The Army decided to take all of the Guard's Apaches and move them into the active component to fill a gap left open upon the retirement of the OH-58 Kiowa Warrior. A commission tasked to study the Army's future force structure is expected to make recommendations on the way ahead at the beginning of February.

Also under consideration is maintaining a high number of leaders on active duty, Milley said. One concept is to build train-and-advise units for overseas deployment that consist of just brigade or battalion leadership.

The Army already uses train-and-advise units, but that involves ripping the leadership out of a unit to use them overseas in that capacity, which "destroys the force structure of those units," Milley said. This time the service would look at building train-and-advise teams that consist solely of unit leaders and then in times of emergency, soldiers could fill in to complete the unit, Milley explained.