People use the term "assault rifle" to mean "assault weapon rifles". It is a very widespread usage, including by politicians and the news media. It is also a very logical usage – it is simply shortening the phrase by dropping "weapon", which is kind of duplicative given it includes "rifle". Yes, this contradicts with the older military usage of the term "assault rifle" – but different people use words in different ways, language evolves, and insisting other people are wrong for using words differently from how you do is just ignorant linguistic prescriptivism.
See [0], "a United States federal law which included a prohibition on the manufacture for civilian use of certain semi-automatic firearms that were defined as assault weapons".
"The Act prohibited the manufacture, transfer, or possession of "semiautomatic assault weapons," as defined by the Act."
0: https://en.m.wikipedia.org/wiki/Federal_Assault_Weapons_Ban