As more nations pull their diplomatic staff out of smoldering Libya, Americans remain optimistic.

Saudi Arabia closed its embassy Monday and evacuated its diplomats, and Turkey shuttered its diplomatic post due to a threat. Just days ago, Algeria also closed its Libyan embassy.

But the U.S. embassy in Tripoli remains open and staffed by Americans -- a sign of the Obama administration's belief that Libya has not passed the tipping point towards chaos.

State Department spokeswoman Jen Psaki on Monday expressed the administration's concern for and awareness of the dire situation, and called on battling sides in the region to "refrain from violence."

Meanwhile, the Defense Department prepared resources to evacuate Americans should the situation get worse, and activated more troops, signaling greater concern.

Two hundred Marines with eight V-22 Osprey aircraft are on standby in Sigonella, Italy, to come to the aid of Americans in Libya on two hours notice. An official from the Department of Defense told ABC News that additional Marines are also being sent to Sicily in the event more manpower is needed.