Seoul, Dec 17 : A US nuclear-powered submarine arrived in South Korea on Sunday, Seoul's Defence Ministry said, amid concerns that North Korea could launch an intercontinental ballistic missile (ICBM) this month. The USS Missouri (SSN-780), a Virginia-class attack submarine, entered a key naval base in Busan, 320 km southeast of Seoul, earlier on Sunday, according to the South Korean Navy. "With the deployment of the USS Missouri, we plan to strengthen naval exchanges and cooperation with the US and to bolster our combined defence posture," it added. The deployment of the submarine comes just three weeks after the USS Santa Fe (SSN-763), a Los Angeles-class submarine, entered the Jeju Naval Base on the southern resort island, Yonhap news agency reported. Earlier this week, Principal Deputy National Security Adviser Kim Tae-hyo raised the possibility of North Korea launching an ICBM in December as he arrived in Washington for a meeting of the Nuclear Consultative Group (NCG), a South Korea-US security meeting designed to discuss nuclear and strategic planning issues. North Korea last test-fired a Hwasong-18 solid-fuel ICBM in July. /IANS