The younger Boston bombing suspect allegedly penned a note on the inside of the boat where he was found hiding from authorities.
The scrawling explained his rationale for his part in the deadly explosion, sources said.
Dzhokhar Tsarnaev allegedly wrote that his actions were retaliations for the U.S. wars in Afghanistan and Iraq.
"When you attack one Muslim, you attack all Muslims," the note said, according to CBS' sources who were granted anonymity.
The report would seem to add credence to a last month story when anonymous "U.S. officials" said Tsarnaev provided a similar rationale for the bombing when he was interrogated from his hospital bed.
In his reaction to the Post's story, Guardian columnist Glenn Greenwald noted that similar reasons have been given by other Muslims who have attempted or carried out recent attacks in America:
In the last several years, there have been four other serious attempted or successful attacks on US soil by Muslims.
And in every case, they emphatically all say the same thing: that they were motivated by the continuous, horrific violence brought by the US and its allies to the Muslim world - violence which routinely kills and oppresses innocent men, women and children.
Greenwald lists attempted "underwear bomber" Umar Farouk Abdulmutallab, attempted Times Square bomber Faisal Shahzad, attempted New York City subway bomber Najibullah Zazi and Fort Hood shooter Nidal Hasan as examples.
"If the United States does not get out of Iraq, Afghanistan and other countries controlled by Muslims, Shahzad said during his guilty plea.
"We will be attacking the U.S."