"We don't need 2.3 million people in uniform, clearly there are economies of scale that NATO ... should do," Jones told reporters.

Reducing staff size would make NATO more efficient including its response force which may act outside Europe, according to the general, who was on a visit to Washington.

To transform US forces and make them lighter, more mobile and better able to manage their finances, the Pentagon is considering creating strategic centers around the world for swift intervention.

"There will a reduction and closure of quite a few NATO headquarters," Jones said.

He cited a US report from 2002 which found 20 percent of the 499 US installations in Europe were "not terribly useful."

SPACE.WIRE