In a global environment of rapid technological, societal and demographic changes, the U.S. Army’s dominance is being challenged by a belligerent Russia and rising China, and war between nation states at some point in the future “is almost guaranteed,” said Army Chief of Staff Gen. Mark A. Milley.

Milley, who assumed duties as the 39th chief of staff in August 2015, spoke during the Dwight David Eisenhower Luncheon at the Association of the U.S. Army’s 2016 Annual Meeting and Exposition.

To meet future challenges, Milley said the Army must rapidly adapt; reform its acquisition process to speed new technologies to the field; build future leaders who can operate on nonlinear battlefields without reliable communications with higher command; and make wise and ethical decisions.

Future adversaries could end the air superiority the U.S. Air Force has provided since the Korean War, Milley said, and anti-access, area-denial capabilities could prevent the Navy from getting to the fight.

So “land forces will have to enable sea forces,” and the Army “is definitely going to have to dominate the air above our battle space,” he said.

Milley also said the Army must be prepared to engage in cyber warfare, operate without the space-based communications and precision navigation it has taken for granted, and fight in a complex urban setting.

While acknowledging the difficulties the Army faces because of budget cuts, reduced forces, and the erosion of its ability to fight “a high-end enemy” after 15 years of focusing on counterinsurgency, Milley issued a blunt warning to “those who try to oppose the United States ... we will stop you and beat you harder than you’ve ever been beaten before.”

The Army is ready to fight and will remain that way, he declared.

But, Milley added, “We must prepare for the future.”

In an unusually hard-edged speech, Milley cited a long list of “fundamental changes” confronting the nation and the Army, including the renewed threat from Russia, the growing economic power and military strength of China, an expanding number of fragile nation states, and climate change that could lead to more instability.

“While we’re ready now, we are being challenged,” he said. If the aim is to deter war, “our Army and our nation must be ready.”

And he offered a “contract with the American people: We, the United States military, the U.S. Army will never lose a war.”

However, he reminded the audience what Army Secretary Eric Fanning had said the day before at the meeting’s opening session: “You have to pay for it.”