Israeli war planes that reportedly struck near the Lebanese border with Syria would either have bombed a convoy of conventional weapons or the nontoxic component of a chemical agent, according to a leading Israeli expert on chemical weapons.

“The chances that someone was able to bomb a chemical weapons convoy without causing significant environmental damage is very small,” Lt. Col. (res) Dr. Dany Shoham, a BESA Center fellow and expert on chemical and biological weapons in the Middle East, told The Times of Israel.

According to officials quoted by AP, the alleged airstrike had in fact hit a truck convoy carrying anti-aircraft missiles bound for the Lebanese Islamist militia Hezbollah.

Unlike, say, a nuclear weapon, which leaves a clear signature in the earth, easily readable by a geologist, chemical agents are often diffused over time and space. The toxic element is carried by the wind, at times spreading for up to 20 kilometers and, though some could be burnt off by the heat and fire of a bomb strike, the effects, Shoham said, would still have “a bigger impact” than what we have seen so far.

Chemical weapons of the sort Syria possess can come in two forms — binary and unitary. A binary weapon is composed of two components — “final precursors” in the technical jargon — that must be mixed together to create the ultimate, toxic result.

“One component is toxic, the other not so much,” Shoham said.

Theoretically, Israeli planes could have hit the less toxic agent, which is possible in principle but hard to imagine in practice, he added.

A unitary agent, either the final product of a mixed agent or not, is already toxic. A nerve agent in that state would likely be already loaded into the warhead of a missile, bomb or artillery shell, meaning that it would require a large convoy to transport. A binary agent could be packed in, say, 10 containers to a single truck, Shoham estimated.

The commander of the Israel Air Force, Maj. Gen. Amir Eshel, spoke on Tuesday of a defensive, offensive and intelligence effort that has taken the form of “a campaign between wars,” and said that while the IAF was making every effort to keep its actions beneath the threshold at which war breaks out, “if there is no choice — it may break out.”

The IAF’s spokesman confirmed that Israel was deeply concerned not just by nonconventional weapons transfers but by an array of state-of-the-art Russian weapons, including surface-to-sea missiles and advanced radars that could change the balance of power between Israel and Hezbollah.