WASHINGTON, December 25, 2004 - The United States invaded Iraq without a formal plan for occupying and stabilizing the country and this continues to undercut the military effort there, the Washington Post on Saturday quoted a U.S. Army historian as saying.

The newspaper quoted Maj. Isaiah Wilson, an official historian of the Iraq campaign, as saying the overall performance of the U.S. Army in Iraq has been "mediocre" and it failed to recognize it is engaged in a "people's war."

As a result, the United States is "perhaps in peril of losing the 'war,' even after supposedly winning it," the Post quoted Wilson as saying.

The critique is significant because it comes from a military insider and strategist who is positioned to be familiar with top-secret planning.

Many Army officers have blamed Defense Secretary Donald Rumsfeld and the Pentagon's civilian leadership for failing to anticipate and plan for the difficult occupation of Iraq. But Wilson reserved his toughest criticism for Army commanders.

According to the Post, he concluded that these commanders failed to grasp the strategic situation in Iraq and no one produced a document laying out the strategy to consolidate victory after major combat operations ended.

Those who planned the war suffered from "stunted learning and a reluctance to adapt," the paper quoted him as saying.

"While there may have been 'plans' at the national level, and even within various agencies within the war zone, none of these 'plans' operationalized the problem beyond regime collapse," Wilson wrote in an essay delivered at several academic conferences but not published, the Post said.

The newspaper said it obtained a copy of Wilson's study as presented at Cornell University in New York in October.