The White House and the Pentagon have repeatedly ruled out "boots on the ground" in Syria, but Defense Department officials were less certain Thursday on whether U.S. military personnel might be sent to help secure or destroy Syria's chemical weapons.

Pentagon Press Secretary George Little gave a vague answer when asked if U.S. troops were prepared to assist should an international agreement allow Russia to take control of the tons of chemical weapons believed to be in the stockpiles of President Bashar al-Assad.

"I'm not going to speculate on who may or may not be participating in a process that may or may not take place," Little said. "We've got to see where the process goes" before the U.S. military considers involvement, he said.

The first steps in the process were taking place in Geneva, where Secretary of State John Kerry was meeting for a second day with Russian Foreign Minister Sergey Lavrov on Moscow's proposal to have international teams take control of the chemical weapons.

Syria has tentatively agreed to the Russian initiative and also agreed to join the international ban on chemical and biological weapons.

Lavrov has urged the U.S. to speed the negotiations by dropping the threat to launch strikes on Syria, but Little said "the threat of military action is driving the process forward."

To back up the threat, the U.S. was keeping four destroyers off the Syrian coast and the Nimitz carrier strike group in the Red Sea, though some of the ships may be replaced if the negotiations are drawn out, Little said.

"We have a mix of assets that would be available" to back up the threat, Little said. He wouldn't comment on whether submarines were also in the Mediterranean to join with the surface ships in launching Tomahawk Land Attack Missiles. Little stressed that "we remain fully prepared to act" in the event that the talks with the Russians fail.

Any strike on Syria would also likely include B-52 bombers and possibly B-2 Spirit bombers firing cruise missiles from "stand-off" positions beyond the range of Syrian air defenses.

In a phone call Friday morning to British Defense Minister Philip Hammond, Defense Secretary Chuck Hagel provided an "update on U.S. activities in the eastern Mediterranean" in response to the alleged Syrian chemical weapons attack on Aug. 21 on the Damascus suburbs, Little said.

Little declined comment on whether Hammond and Hagel discussed the possible use by the U.S. of the British airbase at Akrotiri on Cyprus, which is about 160 miles from the Syrian coast.

Last Sunday, the British Ministry of Defense confirmed that Typhoon interceptors had scrambled from Akrotiri to confront Syrian fighters that had flown into international air space near Cyrpus.

In a statement, the Ministry of Defense said that "Typhoon Air Defense Aircraft operated from RAF (Royal Air Force) Akrotiri to investigate unidentified aircraft to the east of Cyprus; the aircraft were flying legally in international airspace and no intercept was required."

The Syrian planes were believed to have been two Russian-made Sukhoi Su-24 attack aircraft that were flying "low and fast," the Daily Mail newspaper reported.

Before the stunning Aug. 30 vote by the British parliament against the use of force in Syria, Britain had sent six Typhoons to Akrotiri.

"This is purely a prudent and precautionary measure to ensure the protection of UK interests and the defense of our Sovereign Base Areas at a time of heightened tension in the wider region. This is a movement of defensive assets operating in an air-to-air role only," an RAF spokesman said at the time.

At the White House Friday, President Obama discussed Syria with the visiting Amir of Kuwait, Sheikh Jaber al-Ahmad al-Jaber al-Sabah. Kuwait has been one of the Gulf states along with Qatar and Saudi Arabia that have been supplying the rebels in Syria with money and, allegedly, arms.

"Our two countries are in agreement that the use of chemical weapons that we saw in Syria was a criminal act," Obama said. "I shared with the Amir my hope that the negotiations that are currently taking place between Secretary of State Kerry and Foreign Minister Lavrov in Geneva bear fruit."

Obama said "any agreement needs to be verifiable and enforceable and we agreed that, ultimately, what's needed for the underlying conflict is a political settlement."