Seoul, Dec 18 : North Korea fired an unspecified ballistic missile toward the East Sea on Monday, the South Korean military said, just hours after it launched a short-range missile, amid speculation the latest one could be an intercontinental ballistic missile. The Joint Chiefs of Staff (JCS) said it detected the launch but did not give further details, Yonhap news agency reported. North Korea fired a short-range missile from in or around Pyongyang at 10:38 p.m. Sunday, and it flew about 570 km before splashing into the East Sea, according to the JCS. The back-to-back missile launches came after South Korea's First Deputy National Security Adviser Kim Tae-hyo said a few days earlier that the North could fire an ICBM within this month. The firings also came days after Seoul and Washington held the second session of the Nuclear Consultative Group (NCG) and agreed to complete the establishment of guidelines on the planning and operation of a shared nuclear strategy by the middle of next year. Just after Sunday's launch, the North's defence ministry lambasted the NCG meeting as "an open declaration on nuclear confrontation" and criticized the U.S.' deployment of major military assets to the Korean Peninsula this year. The North's latest sabre-rattling also came amid heightened tensions after Pyongyang scrapped a 2018 inter-Korean military agreement designed to reduce tensions and prevent accidental clashes along the border last month. Seoul had partially suspended the deal in protest of the North's successful launch of its first military spy satellite on Nov. 21. The North last fired a ballistic missile on Nov. 22, but the launch apparently failed, according to the JCS. /IANS