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The White House today defended President Obama's decision to apologize for the recent incident of Koran burning at a U.S. airbase in Afghanistan, saying it was "wholly appropriate" given the "understandable sensitivities" to the issue.

"The error was inadvertent," Obama wrote in a letter to his Afghan counterpart Hamid Karzai, according to Karzai's office. "I assure you that we will take the appropriate steps to avoid any recurrence, to include holding accountable those responsible."

Republican presidential candidate Newt Gingrich, however, said it was "an outrage" for the president to issue an apology on the same day two U.S. troops were killed by Afghan soldiers.

"It is Hamid Karzai who owes the American people an apology, not the other way around," Gingrich said in a written statement. "This destructive double standard whereby the United States and its democratic allies refuse to hold accountable leaders who tolerate systematic violence and oppression in their borders must come to an end."

White House Press Secretary Jay Carney defended the apology.

"[The president's] primary concern as Commander-in-Chief is the safety of American men and women in Afghanistan, of our military and civilian personnel there. And it was absolutely the right thing to do," Carney told reporters.

The improper disposal of the sacred text of Islam have sparked anti-U.S. riots in Afghanistan.

"The actions here, while inadvertent, do not reflect the great respect that our military personnel have for the religious traditions of the Afghan people," Carney said.

Gingrich was not the only prominent Republican to slam the president's decision. "Obama apologizes for inadvertent Koran burning; now the US trained & protected Afghan Army can apologize for killing our soldiers yesterday," 2008 Republican Vice Presidential nominee Sarah Palin tweeted this afternoon.

Republican frontrunner Mitt Romney has not spoken directly about the apology to Karzai, but vowing no apology is a key line of his stump speech.

"Let me make this very clear. As President of the United States, I will devote myself to an American Century. And I will never, ever apologize for America," the former Massachusetts governor said in October.

The White House says the president's apology was conveyed before the U.S. troops were killed today.

Furthermore, the administration notes that the apology, which was included in a lengthy three-page letter from Obama to Karzai on a range of issues, is not unprecedented. In 2008, President Bush apologized to Iraq's prime minister for an American sniper's shooting of a Koran.