Two unmanned armed predators capable of around-the-clock coverage are now in Libya, the general added. The first flights launched today but were cancelled because of bad weather.
The character of the fight in Libya has changed, Cartwright said. Gadhafi loyalists, he said, are digging in or "nestling up against crowded areas" to avoid being targeted by NATO aircraft.
The more-precise predators bring "their ability to get down lower and therefore, to be able to get better visibility, particularly on targets that have started to dig themselves into defensive positions," Cartwright said.
The aircraft are uniquely suited for urban areas where more traditional bombing can cause collateral damage, he added.
"This is a very limited capability," Gates said, adding that the president has been clear from the outset that the U.S. role would be specifically defined.
Obama structured the U.S. role in Libya as a limited one because "of all our friends and allies, we are the most-stretched military," Gates added.
"We have close to 100,000 troops in Afghanistan, we still have 50,000 troops in Iraq and we have 19 ships and 18,000 men and women in uniform still helping on Japan relief," the secretary said.
The president agreed to participate in the international effort against the Libyan government, Gates said, because "of the worry that Gadhafi could destabilize the fledgling revolutions in both Tunisia and Egypt ... and second to prevent a humanitarian disaster."
The president has been clear, the secretary said, "that the primary strike role has been turned over to our allies and our friends, and if we can make a modest contribution with these armed predators, we'll do it."