GOP presidential candidate Newt Gingrich is expressing outrage over a U.S. apology to Afghan authorities for burned Qurans on a military base.

He was joined by Sarah Palin, who blasted the decision on her Facebook page: “Obama apologizes for the inadvertent Quran burning this week; now the U.S. trained and protected Afghan Army can apologize for killing two of our soldiers yesterday.”

Gingrich lashed out Thursday at the Obama administration for the formal apology. Copies of the Muslim holy book were found burned in a garbage pit on a U.S. air field.

President Barack Obama’s apology was announced Thursday morning. A few hours later, news organizations reported that an Afghan soldier had killed two U.S. troops and wounded others in retaliation for the Quran burning.