What to know about the 100 US 'Switchblade' drones heading to Ukraine

In a White House list of weapons being sent to Ukraine as part of a new $800 million military support package announced by President Joe Biden Wednesday -- among nearly 10,000 anti-armor weapons, 800 anti-aircraft Stinger systems, and thousands of rifles -- appeared 100 "tactical unmanned aerial systems."

But these aren't the large U.S. drones you're used to seeing.

The 100 unmanned systems heading to Ukraine are actually small "Switchblade" drones, a U.S. official told ABC News.

Unlike long-range Predator drones, which look similar to small planes and fire missiles at targets, the smallest Switchblade model fits in a rucksack and flies directly into targets to detonate its small warhead.

Less than 2-feet long and weighing only 5.5 pounds, the Switchblade 300 can be launched from a small tube that resembles a mortar, after which it can fly for up to 15 minutes. The larger Switchblade 600 is effective against armored targets and can fly for more than 40 minutes, but weighs 50 pounds, according to the manufacturer.

The U.S. official could not say whether one or both of the systems would be included in the 100 units destined for Ukraine.

Both Switchblades use onboard sensors and GPS to guide them to their targets. Both also have a "wave-off" feature so that human operators can abort an attack if civilians appear near the target or if the enemy withdraws.

"These were designed for U.S. Special Operations Command and are exactly the type of weapons systems that can have an immediate impact on the battlefield," said Mick Mulroy, former deputy assistant secretary of defense and an ABC News national security and defense analyst.