The U.S. and South Korea have begun a six-day joint naval drill in South Korea, with the participation of a U.S. nuclear-powered aircraft carrier.

The drill comes amid growing speculation that Pyongyang might conduct new nuclear test or ballistic missile launch.

The “Invincible Spirit 2016” drill will last from Monday to Saturday, in all waters around the Korean peninsula.

The U.S. has deployed nuclear-powered aircraft carrier “USS Ronald Reagan” along with seven warships. And South Korea has mobilized about 40 warships.

A spokesman from the South Korean navy said the exercises are aimed at countering the relentless provocations by the DPRK.