Alphabet's Google needs strong measures imposed on it to prevent it from using its artificial intelligence products to extend its dominance in online search, a U.S. Department of Justice attorney said as trial in the historic antitrust case began on Monday.

The outcome of the trial could fundamentally reshape the internet by unseating Google as the go-to portal for information online.

Google on Monday will confront an existential threat as the U.S. government tries to break up the company as punishment for turning its revolutionary search engine into a ruthless monopoly.