Yonhap quoted a South Korean official who said the Tucson "had left" and that the U.S. Navy "did not disclose its next destination".
Anti-aircraft and anti-ship guns will be fired during the exercise, the navy added.
A second South Korean official who spoke anonymously said US forces are "irregularly" being deployed to the peninsula to participate in drills and joint training, and without disclosing deployment ahead of time, according to Yonhap.
Cmdr. Chad Hardt, commanding officer of the Tucson, said the deployment gives the Navy an "opportunity to strengthen the outstanding relationship that exists between the US and the Republic of Korea".
As a rule, the US Navy does not comment on future operations, but the Reagan has been spotted in Korea's vicinity recently. As the U.S. Navy's largest numbered fleet, 7th Fleet interacts with 35 other maritime nations to build maritime partnerships that foster maritime security, promote stability and prevent conflict.
Washington has in recent days attempted to ramp up pressure on Pyongyang by deploying strategic military assets to the Korean peninsula.
The US Navy's USS Michigan attack submarine arrived in Busan, South Korea's southern port city, on Friday, and it looks like it will be joined by a US aircraft carrier in a bold challenge to a defiant North Korea, Yonhap news reports.
At just over 170 meters long, it is one of the world's biggest submarines, capable of conducting underwater operations for more than three months.
MI is one of four Ohio-class guided-missile submarines, which are meant to provide both tactical strike and special operation mission capabilities from a "stealthy, clandestine platform".
The submarine was originally outfitted with Trident ballistic missiles, but now carries up to 154 Tomahawk cruise missiles-the equivalent of an entire surface battle group.