The Pentagon on Thursday detailed US President Joe Biden's latest $800 million military aid package to Ukraine.

Pentagon spokesman John Kirby said it includes 72 155mm Howitzer heavy artillery systems, 144,000 associated rounds and 72 vehicles to tow the Howitzers. It also includes 121 Phoenix Ghost drones, as well as unspecified field equipment and spare parts.

"This commitment, together with the 18 155mm howitzers announced on April 13, provides enough artillery systems to equip five battalions," Kirby said in a statement.

"The United States has now committed more than $4 billion in security assistance to Ukraine since the beginning of the Biden Administration, including approximately $3.4 billion since the beginning of Russia’s unprovoked invasion on February 24," he said.

Commenting on the Phoenix Ghost drones, a senior defense official said the Pentagon will provide the Ukrainian military with the same capability as the already-provided Switchblade drones. The Phoenix Ghost drones were developed by the Air Force "to specifically address some Ukrainian requirements," he said.

The drones are what are known as loitering munitions, or suicide drones, which target a vehicle or personnel and ram into them with attached explosives.

The US has not specified which variant, or variants, of the 155mm Howitzer it is providing. But the M177 and M198 models are both towed by a vehicle.

The M177 has a maximum range of 19 miles (30 kilometers), depending on the type of round, while the M198 has the same range, but is about 7,000 pounds heavier, according to the army.