The U.S. military has intercepted a letter in which senior Al Qaeda operatives reveal their fury over militants' failure to keep up with the campaign against U.S.-led forces in Iraq, U.S. General David Perkins told FOX News Wednesday.

The letter, dated March 6, 2008, has been reproduced with select quotes in English.

It was found on the body of Abu Nizar, believed to be the go-between between Al Qaeda's second in command, Ayman al-Zawahiri, and Abu Ayyub al-Masri, his leader in Iraq.

Nazir was killed by Coalition Forces in Baghdad on April 24.

The letter blasts Al Qaeda in Iraq for failing to maintain communication and for poorly-planned attacks. Al Qaeda leaders also slam operatives for sending fighters into battle alone, without direction.

Al-Zawahiri also criticizes them for posting videos online using archive footage of violent attacks, yet presenting them as new evidence of their success.

The letter reads, "[Aby Ayyub al-Masri]... is not strong enough to bear this great great responsibility, and is weak at [...] decision making. He is weak [...] he is totally isolated [..] this is affecting his grip on reality."

The United States military said Al Qaeda in Iraq responded to the criticism with claims of being financially cut off, and unable to recruit capable new members.

Perkins told FOX News the communications show that Al Qaeda in Iraq is "psychologically bankrupt,” and that it cannot raise meaningful support within in the country. He added that the numbers of Al Qaeda operatives in Iraq are a third of what they were previously. When asked what those levels were, Perkins would not release numbers.

FOX News' Dominic Di-Natale contributed to this report from Baghdad.