Crippling US drone attacks forced Osama bin Laden to consider withdrawing his fighters from what had previously been safe havens in Pakistan, according to newly released documents seized at the compound where the al-Qaida leader was killed a year ago.

Memorandums between Bin Laden and his subordinates, made public by the US military's Combating Terrorism Center on Thursday, also revealed that with support eroding in the Muslim world because of the large number of civilians killed by al-Qaida and its affiliates, he wanted to focus "every bow and arrow" at US targets even at the expense of attacks on other countries, such as Britain, and Nato forces. Bin Laden said it would be a good idea to kill Barack Obama because then an "utterly unprepared" Joe Biden would become president.

But while the al-Qaida leader plotted the downfall of the US, he was forced to acknowledge that American drone attacks were taking a toll on his followers in Afghanistan and Pakistan's Waziristan region, and to contemplate withdrawing forces. He wrote:

Bin Laden said the air attacks made it necessary to keep reserves back from the "front line".

"The reserves will not, for the most part, be effective in such conflicts. Basically, we could lose the reserves to enemy's air strikes. We cannot fight air strikes with explosives!" he said.

He also said that commanders with experience needed to be got out of the area:

In another document, the al-Qaida leader recommends his fighters keep "a low profile":

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For all of that, Bin Laden asserted that the US was losing in Afghanistan:

Another document, likely to have been written by Bin Laden but possibly another senior leader, calls for a refocusing on the United States as a target.

It says that America should be driven from the Islamic world in part so it "could not threaten or defeat any state which we create". The document said that to reach that goal attacks on Washington's allies, such as Britain, and Nato should largely be abandoned in order to concentrate on the US.

The writer likens America to a tree trunk with branches that represent its Nato allies and friendly governments in the Arab world:

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Bin Laden proposed assassinating Obama in order to bring Biden, described as "utterly unprepared", to power and throw the US into chaos. He ordered his forces to create two teams that could hit Obama if he travelled to Pakistan or Afghanistan. The then-US military commander in Afghanistan, general David Petraeus, was also a favoured target.

The American al-Qaida spokesman Adam Gadahn in one document discusses how to win support in the US and other countries. He says that the cause is not helped by attacks such as a massacre by al-Qaida of worshippers at a Baghdad Catholic church. He said that Catholics are more likely than other Christians to be more sympathetic to Muslims and causes supported by al-Qaida, including over Palestine. He wrote:

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Outside of the Middle East, Gadahn proposed focusing on winning support in Ireland, partly in the hope that anger toward the Catholic church over child abuse might turn people toward Islam. He wrote: