BALTIMORE — The Army must continue to be ready at a moment's notice for whatever crisis threatens America or its allies, Chief of Staff Gen. Mark Milley said Saturday.

"The readiness of that Army will remain our No. 1 priority. We have no other choice," Milley said, addressing the National Guard Association of the United States annual conference. "We must remain prepared. We can never break faith with the American people. We owe that to them, we signed up for it, we took an oath to it, and we will not fail."

Speaking on the eve of the 15th anniversary of the Sept. 11, 2001, terrorist attacks, Milley said that the threat posed by extremists has not lessened.

"Those people, those enemies, those members of that terrorist group, still intend — as they did on 9/11 — to destroy your freedoms, to kill you, kill your families, they still intend to destroy the United States of America," he said.

The military, Milley noted, has been fighting the Global War on Terror for a decade and a half since 2001.

"All our lives, all our destinies were forever changed in those moments and we have been at war for 15 consecutive years," he said. "And so many soldiers, airmen, sailors and Marines, so many guardsmen have given their lives and their limbs and all of you have made sacrifices in the defense of that freedom."

It's a fight that Milley doesn't see ending anytime soon.

"That mission, that task, is likely to remain for quite some time," he said.

That's why the chief said he's placing so much emphasis on readiness, for both active duty and Guard units.

"The possibility of armed conflict is real, and the time available to mobilize and deploy … might not be available in the next conflict," he said.

The Army, Milley said, is looking at taking "very concrete steps" to improve the readiness of guardsmen.

"In 2016 we had two Guard brigade combat teams go to decisive action rotations," he said, noting that two will also go for training in 2017.

"By 2018, we want to have, and we put into the budget, that we're going to double that to four," Milley added. "So we'll have four Army National Guard brigade combat teams go to decisive action training [at] combat training centers."

And for guardsmen, "we're going to increase the training days," Milley said, acknowledging that it's going to be a challenge. "Increasing training days has proven to come off my lips pretty easy … I'm going to do it, though."

The Guard needs to be ready because it has become such an integral part of Army operations, the general said.

"This year, we will see four of the eight National Guard divisions deploy in one capacity or another," Milley said.

And on the home front, Guard units have been involved in aid and recovery operations for the historical flooding in Louisiana, Hurricane Hermine that hit Florida and the East Coast, and wildfires that are spreading across California and the western U.S.

"Our nation's ability to protect not only our oversees interests but respond to natural disasters here at home and protect the American people, our ability to do that would not exist without the American National Guard," Milley said.

The general emphasized that the National Guard is a critical part of all military operations, and compared the different branches of the Army — active duty, Guard and Reserve — to water.

"Just as water can exist in three states, a solid, a liquid, and a gas, we have one Army," Milley said. "We're not an army of 10 divisions, we're an army of 18 divisions … We were one Army a year ago, and we're one Army today, and we're going to remain one Army forever."