It is a chilling vision of war - and one unlike any other ever fought.

US military bosses have revealed their predictions for a major conflict, and say war between nation states at some point in the future "is almost guaranteed".

Artificial intelligence and smart weapons would be at the fore - with a "modern nation-states acting aggressively" the likely enemy

"A conventional conflict in the near future will be extremely lethal and fast, and we will not own the stopwatch,' said Major General William Hix on a future-of-the-Army panel at the annual meeting of the Association of the U.S. Army in Washington, according to Defence One.

Advertisement

"The speed of events are likely to strain our human abilities,' Hix said.

"The speed at which machines can make decisions in the far future is likely to challenge our ability to cope, demanding a new relationship between man and machine."

China and Russia are both mustering conventionally massive militaries that are increasingly technological - and forcing the Pentagon to contemplate and prepare for "violence on the scale that the U.S. Army has not seen since Korea," said Hix .

Lt. Gen. Joseph Anderson, Army deputy chief of staff for operations, plans, and training said the US faces threats from "modern nation-states acting aggressively in militarised competition."

"Who does that sound like? Russia?" he said.

War between nation states at some point in the future 'is almost guaranteed,' said Army Chief of Staff Gen. Mark A. Milley at the same event.

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, he warned.

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 said the Army also 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.

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."

The Army's future weapons will also need to be better designed, Katharina McFarland, acting assistant Army secretary for acquisition, logistics, and technology said.

"You travel all over the world, don't you?' McFarland asked the gathered audience of soldiers, Army civilians, and industry reps.

"You can pretty much get in a car anywhere and drive it."

"As an engineer, I think in terms of a simple interface - no matter what helicopter, you can get in and operate it."