Slain al-Qaeda mastermind Osama bin Laden plotted to kill President Barack Obama because he believed Vice President Joe Biden was ill-prepared to lead the country, according to soon-to-be released declassified documents first obtained by The Washington Post.

Osama bin Laden also wanted to kill Gen. David Petraeus and ordered al-Qaeda to set special terror cells into motion to take action, although the plots were never a serious threat, the Post reported.

The cells were to attack planes carrying President Obama and Petraeus that were flying over Afghanistan and Pakistan.

Why did bin Laden want to assassinate the president?

Obama is the head of infidelity and killing him automatically will make (Vice President Joe) Biden take over the presidency. ... Biden is totally unprepared for that post, which will lead the U.S. into a crisis, bin Laden said to a top lieutenant, according to the Post. As for Petraeus, he is the man of the hour ... and killing him would alter the war's path in Afghanistan.

The Washington Post obtained the documents, which are declassifed and will soon be made available to the public. They were taken from the May 2 raid on bin Laden's compound in Abbottabad, Pakistan.

Bin Laden was shot and killed during the raid.