The State Department has just issued a worldwide travel warning, alerting Americans overseas to the possibility of violent demonstrations and reprisals if a Florida pastor goes through with stated plans to burn copies of the Quran, Islam's holy book, on Saturday.

"The Department of State is issuing this Travel Alert to caution U.S. citizens of the potential for anti-U.S. demonstrations in many countries in response to stated plans by a church in Florida to burn Qurans on the anniversary of the September 11, 2001 terrorist attacks," says the warning, known as a Worldwide Caution.

"Demonstrations, some violent, have already taken place in several countries, including Afghanistan and Indonesia, in response to media reports of the church's plans," it says. "The potential for further protests and demonstrations, some of which may turn violent, remains high.  We urge you to pay attention to local reaction to the situation, and to avoid areas where demonstrations may take place."

U.S. leaders from President Barack Obama to Secretary of State Hillary Clinton and Afghanistan commander Gen. David Petraeus have spoken out against the event, planned by the Rev. Terry Jones, pastor of the Gainesville, Fla.-based Dove Outreach Center.

Clinton on Wednesday sent a cable to all U.S. diplomatic posts overseas, instructing ambassadors and their staffs to interact with foreign governments and publics to convey the message that the Quran-burning, if it takes place, does not reflect U.S. values.