WASHINGTON (Reuters) – U.S. military leaders voiced concern on Wednesday about their ability to fight a war with global powers like Russia, telling a congressional hearing that a lack of resources and training was weighing on America’s combat readiness.

U.S. Army Chief of Staff General Mark Milley told a House Armed Services Committee hearing that if the Army were to fight a “great power war” with China, Russia, Iran or North Korea, he had “grave concerns” about the readiness of his forces.

“(The Army) is not at the levels that can execute satisfactorily … in terms of time, cost in terms of casualties or cost in terms of military objectives,” Milley said.

Also speaking at the hearing, about the Fiscal 2017 budget request for the military, Air Force Secretary Deborah James said half of her combat forces were not “sufficiently ready” for fighting against a country like Russia.

“Money is helpful for readiness but freeing up the time of our people to go and do this training is equally important,” James said.

Earlier this month Air Force officials said they were facing a shortage of more than 500 fighter pilots, a gap expected to widen to more than 800 by 2022.

U.S. military spending has increased sharply since the Sept. 11, 2001, attacks and the country has by far the largest military budget in the world.

The Army requested $148 billion in the fiscal 2017 budget, a slight increase from the $146.9 billion Army budget for 2016.

However, the 2017 Army budget would continue to shrink the size of the U.S. Army, which will drop to 460,000 active duty soldiers in 2017 from the current 475,000.

Concern over a more assertive Russia was highlighted earlier this month by Air Force General Philip Breedlove, the NATO supreme allied commander and head of U.S. European Command, when he said Russia posed a “long-term existential threat to the United States.”

(Reporting by Idrees Ali; Editing by Tom Brown)