North Korea says it is cutting a military hotline with the South March 27, 2013 -- Updated 1031 GMT (1831 HKT) The announcement follows a slew of recent threats from North Korea The move will affect people working in a joint North-South industrial complex South Korea calls for the measure to be withdrawn It comes during joint military exercises by the United States and South Korea Yeonpyeong Island, South Korea (CNN) -- North Korea said Wednesday it was cutting off a key military hotline with South Korea amid high tensions between the two sides. "Under the situation where a war may break out any moment, there is no need to keep north-south military communications," the head of a North Korean delegation told the South by telephone Wednesday, according to the North's state-run Korean Central News Agency. The North linked the move to annual joint military exercises by South Korea and the United States, which it has cited in a string of threats against the two countries in recent weeks. Tougher sanctions approved by the U.N. Security Council have also fueled its anger. There are several hotlines between North and South Korea. Earlier this month, Pyongyang disconnected a humanitarian hotline that ran through the border village of Panmunjom, according to the South Korean Unification Ministry. The North's announcement Wednesday appeared likely to affect the movement of people in and out of the Kaesong Industrial Complex, a joint economic cooperation zone between the two Koreas situated on the North's side of the border. "The measure taken by North Korea is not beneficial for the stable operation of the Kaesong Industrial Complex, and we urge them to withdraw the measure," the Unification Ministry said. The ministry said that it has confirmed that South Koreans who had entered the complex Wednesday were safe. It said it planned to find a way to ensure the safe entry of people to the complex in the future. Officials won't know for sure if the hotline they use for Kaesong has been cut off until Thursday, according to the ministry. It said that so far, it hadn't noted any issues with other hotlines, such as those used for aviation and maritime controls. The North previously cut off the Kaesong hotline in March 2009 -- also during annual U.S.-South Korean military exercises -- but reinstated it in 2010, according to the semiofficial South Korean news agency Yonhap. The slew of recent fiery rhetoric from Pyongyang has included threats of pre-emptive nuclear strikes against the United States and South Korea, as well as the declaration that the armistice that stopped the Korean War in 1953 is no longer valid. On Tuesday, the North said it planned to place military units tasked with targeting U.S. bases under combat-ready status. CNN's K.J. Kwon reported from Yeonpyeong Island, and Jethro Mullen reported and wrote from Hong Kong.