The Syrian military is prepared to use chemical weapons against its own people and is awaiting final orders from President Bashar Al-Assad, U.S. officials told NBC News on Wednesday.

The military has loaded the precursor chemicals for sarin, a deadly nerve gas, into aerial bombs that could be dropped onto the Syrian people from dozens of fighter-bombers, the officials told the American network.

As recently as Tuesday, officials had said there was as yet no evidence that the process of mixing the “precursor” chemicals had begun. Reports on Monday indicated that engineers working for the Assad regime have begun combining the two chemical precursors needed to weaponize sarin gas.

But Wednesday, the officials said, the nerve agents were locked and loaded inside the bombs.

The officials stressed that as of now, the sarin bombs hadn’t been loaded onto planes and that Assad hadn’t issued a final order to use them. But if he does, one of the officials said, “There’s little the outside world can do to stop it.”

Meanwhile, U.S. Secretary of State Hillary Clinton reiterated her country’s warnings to Assad not to use chemical weapons, saying he would be crossing “a red line” if he did so.

Speaking Wednesday at NATO headquarters in Brussels, Clinton said the Syrian government was on the brink of collapse, raising the prospect that “an increasingly desperate Assad regime” might turn to chemical weapons or that the banned weapons could fall into other hands.

The Syrian government said this week that it wouldn’t use chemical weapons on its own people and President Barack Obama warned that doing so would be “totally unacceptable.”

But U.S. officials said this week that the government had ordered its Chemical Weapons Corps to “be prepared,” which Washington interpreted as a directive to begin bringing together the components needed to weaponize Syria’s chemical stockpiles.

Sarin is an extraordinarily lethal agent. Iraqi President Saddam Hussein’s forces killed 5,000 Kurds with a single sarin attack on Halabja in 1988.

Prime Minister Binyamin Netanyahu said on Tuesday that Israel is closely monitoring Syria’s potential use of chemical weapons.

“Together with the international community, we are closely monitoring developments in Syria regarding its stores of chemical weapons,” said Netanyahu. “I heard President Obama’s important remarks on this issue and we are of the same mind, that such weapons must not be used and must not reach terrorist elements.”

Israel has expressed concern that the chemical weapons arsenal maintained in Syria will indeed end up in the wrong hands – specifically, the hands of Hizbullah or other terrorists who aim to annihilate the Jewish State.