Behind the use of barrel bombs in Syria

The White House walked back a statement suggesting their use was a red line.

At Monday's briefing, Spicer told reporters, “The answer is if you gas a baby, if you put a barrel bomb into innocent people I think you will see a response from this president. Make no mistake he will act.”

Press Sec. on Syria, citing gas and barrel bombs: "If we see this kind of action again, we hold open the possibility of future action." pic.twitter.com/xMFPeSNBHq

— ABC News (@ABC) April 10, 2017

"Nothing has changed in our posture," a White House spokesman told ABC News on Monday night, clarifying Spicer's comment. "The president retains the option to act in Syria against the Assad regime whenever it is in the national interest, as was determined following that government's use of chemical weapons against its own citizens." Last week, the U.S. fired cruise missiles at a Syrian air base in response to a chemical attack that killed over 80 men, women and children in Khan Sheikhou. The Syrian government has denied carrying out the attack.

To build a barrel bomb, an explosive device and shrapnel are packed into a barrel-like container. Then, the bombs are dropped from planes and helicopters without any guidance equations to specify where they land. In the case of the Assad regime, this has led to indiscriminately targeting civilians and high casualty rates.

"We're seeing use of another egregious weapon, this kind of barrel bomb, which is an incendiary bomb that contains flammable materials," State Department spokesperson Victoria Nuland said in December of that year. "It's sort of a napalm-like thing, and it's completely indiscriminate in terms of civilians, so very, very concerning and indicative of the regime's desperation and the regime's brutality."

The makeshift bomb then resurfaced in various civil wars around the world before coming to prominence once again in Syria.

ABC News' Luis Martinez contributed to this report.

Press Sec. on Syria, citing gas and barrel bombs: "If we see this kind of action again, we hold open the possibility of future action." pic.twitter.com/xMFPeSNBHq

"Nothing has changed in our posture," a White House spokesman told ABC News on Monday night, clarifying Spicer's comment. "The president retains the option to act in Syria against the Assad regime whenever it is in the national interest, as was determined following that government's use of chemical weapons against its own citizens." Last week, the U.S. fired cruise missiles at a Syrian air base in response to a chemical attack that killed over 80 men, women and children in Khan Sheikhou. The Syrian government has denied carrying out the attack.

To build a barrel bomb, an explosive device and shrapnel are packed into a barrel-like container. Then, the bombs are dropped from planes and helicopters without any guidance equations to specify where they land. In the case of the Assad regime, this has led to indiscriminately targeting civilians and high casualty rates.

"We're seeing use of another egregious weapon, this kind of barrel bomb, which is an incendiary bomb that contains flammable materials," State Department spokesperson Victoria Nuland said in December of that year. "It's sort of a napalm-like thing, and it's completely indiscriminate in terms of civilians, so very, very concerning and indicative of the regime's desperation and the regime's brutality."

The makeshift bomb then resurfaced in various civil wars around the world before coming to prominence once again in Syria.

ABC News' Luis Martinez contributed to this report.