The U.S. is sending a nuclear-powered submarine and aircraft carrier striker group to waters near the Korean Peninsula amid ever-increasing tensions with North Korea, according to a source on Monday.

The USS Michigan submarine is to enter Busan port this weekend, while the USS Ronald Reagan will arrive next week. The Michigan was here in April as well.

The sub is armed with 154 Tomahawk missiles that are capable of striking the North's nuclear and missile facilities and Kim Jong-un's presidential palace with pinpoint accuracy.

It is 170.6 m long and has a displacement of 18,000 tons. It is capable of staying underwater for up to three months. Its Tomahawk missiles can accurately strike targets 1,600 to 2,300 km away.

The source said that they will take part in a joint South Korea-U.S. drill next week in preparation for a fresh provocation by North Korea.