WASHINGTON, Feb 23 (Reuters) - Defense Secretary Chuck Hagel will propose on Monday a reduction in the size of the U.S. Army to its smallest size since before World War Two and scrapping a class of Air Force attack jets, the New York Times reported on Sunday.

The plans, which the paper said were outlined by several Pentagon officials on condition of anonymity, would be aimed at reducing defense spending in the face of government austerity after a pledge by President Barack Obama to end U.S. involvement in wars in Iraq and Afghanistan.

It would leave the military capable of defeating any enemy but too small for long foreign occupations, and would involve greater risk if U.S. forces were asked to carry out two large-scale military actions at the same time.

"You have to always keep your institution prepared, but you can't carry a large land-war Defense Department when there is no large land war," the Times quoted a senior Pentagon official as saying.

It added that some of the plans may face political opposition in Congress, but quoted the officials as saying that they had the endorsement of the Joint Chiefs of Staff.