"assault group" is a correct and usable phrase in written English.
You could use it to refer to a group of people who are doing or planning an assault or attack of some kind. For example, "The government sent an assault group into the city to take back control from the rebels."
When Seal Team Six was chosen for the Bin Laden mission, he requested to be part of the assault group that would enter the house.
The largest anti-sexual assault group in the US has condemned Maroon 5's new video as "a dangerous depiction of a stalker's fantasy".
The measures include building a processing centre for asylum-seekers on Christmas Island, off the north-west coast, setting up a second counter-terrorist tactical assault group and establishing a regiment to respond to chemical and biological attacks.
In addition, nearly two dozen American ships are operating in the North Arabian Sea, including nuclear-powered submarines, an amphibious assault group carrying the 15th Marine Expeditionary Unit and two aircraft carriers, the Theodore Roosevelt and the Carl Vinson.
After capturing the radar and other installations, the assault group dismantled the equipment then withdrew towards the beach.
The assault group comprised a reinforced company of six infantry platoons and an attached platoon of Royal Engineers.
Two companies of ARVN troops, organized into three assault groups, climbed into the helicopters.
Rebels are attacking the town with assault groups backed by artillery and armoured vehicles," the ministry said, according to Reuters.
One of the assault groups was commanded by Opio Makas, a former high-level L.R.A. commander who had been abducted when he was twelve.
Officials in Kashgar said a leader of one of the assault groups had trained in Pakistan, while a little-known Islamic group claimed the attacks were retaliation for the government's repression of the region's Uighur population.
At the same time, Mr. Rumsfeld directed the Navy to keep two aircraft carriers and two Marine amphibious assault groups ready to be sent to the gulf on 96-hour notice.
