Obama, Cameron Agree to 'Full Spectrum of Possible Responses' on Libya

President Obama and British Prime Minister David Cameron agreed Tuesday to plan for the "full spectrum of possible responses" on Libya including an arms embargo and a no-fly zone.

The White House emphasis on a full spectrum of responses, in a statement on a phone call Tuesday between the two leaders, underscored the potential for a military response from the U.S. and its NATO allies as Libya slips from Moammar Gadhafi's grip and into civil war.

The White House said Obama and Cameron agreed that the objective must be an end to violence and the departure of Gadhafi "as quickly as possible."

The two "agreed to press forward with planning, including at NATO, on the full spectrum of possible responses, including surveillance, humanitarian assistance, enforcement of the arms embargo, and a no-fly zone," the White House said.

Enforcing a no-fly zone would likely involve a complex commitment of U.S. military might, but there have been increasing calls for one as forces loyal to Gadhafi hammer rebels with airstrikes. The estimates of deaths range from hundreds to thousands.

The president's most senior national security advisers are to meet Wednesday to outline what steps are realistic and possible to pressure Gadhafi to end the violence and leave power, officials said.

A meeting of the president's highest level advisers held at the White House will examine the ramifications of a no-fly zone over Libya and potential military options, although the final decision will rest with Obama, the officials said, speaking on condition of anonymity to discuss internal administration deliberations.

Secretary of State Hillary Rodham Clinton, National Security Adviser Tom Donilon and CIA chief Leon Panetta are among those expected to attend, the officials said. Defense Secretary Robert Gates is abroad, but someone from his staff will represent the department, they said.