By Samuel Axon at Mashable

An organization called Rethink Afghanistan has executed a widespread war protest on the White House’s Facebook page.

It began with a drive for 20,000 signatures at Rethink Afghanistan’s website, but folks who added their signatures were also given instructions for participating in the Facebook () protest.

Hundreds of people have posted the following message or something very close to it to the White House page:

“President Obama, I am one of more than 20,000 signers of this petition from Rethink Afghanistan: ‘In your State of the Union address on January 27, 2010, I want you to provide a concrete exit strategy for our troops in Afghanistan that begins no later than July 2011 and which completes a withdrawal of combat troops no later than July 1, 2012.’ Petition: http://bit.ly/7romlW“

The posts link back to the petition page outside Facebook, soliciting more signatures and thus training more people to participate in the protest. We’re not sure how many people have posted on the White House’s wall in the protest, but as the message says, more than 20,000 have signed the petition.

Rethink Afghanistan has set up a Ustream embed on its own Facebook page, where it will air the anti-war documentary Cost of War with an introduction by Robert Greenwald at 7:15 p.m. EST tonight. After the one-hour documentary, Greenwald will answer questions leading up to the president’s State of the Union, which will also stream on the Facebook page.

Regardless of your political stance, this is an interesting (but not surprising) use of social media. Do you think social media protests could have an impact on policy?