By Phil Stewart and Susan Cornwell
WASHINGTON (Reuters) - The Pentagon defended its decision not to deploy forces to Benghazi, Libya, as soon as the U.S. mission came under attack on September 11th, saying it would have been irresponsible to put forces in harm's way without better information.
President Barack Obama's response to the attacks in Libya has been a contentious issue in the hard-fought U.S. presidential race, with Republican opponents raising questions about his administration's truthfulness and competence.
Obama supporters have in turn accused Republicans of making unfounded accusations in an effort to score political points from the death of a U.S. ambassador and the three others killed in the Benghazi attack.
The Speaker of the House of Representatives, Republican John Boehner, asked in a letter to Obama on Thursday about whether military options and assets were offered "during and in the immediate aftermath of the terrorist attack."
"Can you explain what options were presented to you or your staff, and why it appears assets were not allowed to be pre-positioned, let alone utilized?" Boehner asked.
Defense Secretary Leon Panetta told Pentagon reporters that U.S. forces were on a heightened state of alert already because of the 11th anniversary of the September 11, 2001, attacks on New York and Washington by al Qaeda.
But he said there simply wasn't enough information to responsibly deploy forces to Libya at the time of the attack.
"You don't deploy forces into harm's way without knowing what's going on, without having some real-time information about what's taking place," Panetta said.
Lacking that information, Panetta said he, General Martin Dempsey, chairman of the U.S. military's Joint Chiefs of Staff, and General Carter Ham, head of the U.S. military's Africa Command, felt they couldn't "put forces at risk in that situation."
"This happened within a few hours and it was really over before, you know, we had the opportunity to really know what was happening," Panetta said.
In the aftermath of the attack, Panetta reminded reporters that the Pentagon deployed a Marine fleet anti-terrorist security team to Tripoli and had Navy ships off the coast.
"And we were prepared to respond to any contingency. And certainly had forces in place to do that," he said.
The administration initially attributed the violence to protests over an anti-Islam film and said it was not premeditated. Obama and other officials have since said the incident was a deliberate terrorist attack.
U.S. Secretary of State Hillary Clinton has attributed the shifting explanation to "the fog of war."
A State Department email made public this week showed that two hours after the attack on the U.S. diplomatic mission compound in Benghazi, the Department's Operations Center advised officials at various U.S. agencies that a militant group called Ansar al-Sharia had claimed credit on Twitter and Facebook for the attacks.
U.S. officials, including Clinton, on Wednesday said that such Internet postings did not constitute hard evidence of who was responsible for the attacks.
The State Department has set up an independent review board to investigate the background and response to the attacks.
The U.S. Senate intelligence committee on Thursday said it will hold hearings in November - after the November 6 presidential election - on security and intelligence issues raised by the September 11 attack in Libya.
(Additional reporting by Mark Hosenball; Editing by Jim Loney)