South Korea and the United States on Monday commenced Iron Mace, a military drill that aims to explore ways to integrate Washington's nuclear and South Korea's conventional capabilities to bolster deterrence against North Korean threats. The tactical exercise is taking place at Camp Humphreys, the primary base for US forces in South Korea. It is designed to improve the responses of allied forces and reinforce deterrence against North Korea's nuclear and missile threats. "I do not think the timing of Iron Mace is in response to any particular event, but it is an overdue exercise to learn effective ways to prevent and counter a possible North Korean nuclear threat," said Chun In-bum, a retired lieutenant general in the South Korean army and now a senior fellow with the National Institute for Deterrence Studies. "And even though we may not be able to link these exercises with a single event in the North, it is clear that the North is becoming increasingly militarily capable and the alliance needs to be prepared for a possible nuclear scenario on the peninsula in order to prevent it," he told DW. Low birth rates shrink South Korea's military 01:16 How did North Korea react? The Iron Mace exercise is being held for the third time after drills in August 2024 and April this year, with each version expanding in scale and complexity, although the militaries of both South Korea and the US are keeping the operational details secret. The drill coincides with another exercise called Freedom Edge 25, a three-way air and maritime exercise involving units from the US, South Korea and Japan in waters off eastern and southern Korea. The maneuvers will include air defense exercises, medical evacuation, maritime interdiction and stepping up ballistic missile defense capabilities. The maneuvers have clearly agitated the North Korean government. Kim Yo Jong, the powerful sister of North Korea's leader Kim Jong Un, condemned the exercises. "Reckless muscle-flexing by the US, Japan and South Korea in the wrong location … will definitely bring about unfavorable consequences," the state-run Korean Central News Agency quoted Kim as saying. She added that Pyongyang would consider the exercises as a "display" and a continuation of the confrontational stance adopted by successive governments in Seoul. North Korea continues to back Russia's war against Ukraine 03:05 Strengthening the alliance between Seoul and Washington North Korean state media also played up reports of Kim Jong Un attending the ground test of a new high-thrust solid-fuel engine for a new generation of advanced intercontinental ballistic missiles that is made of composite carbon fiber, with the North Korean leader declaring the breakthrough a "significant change" in enhancing the nation's nuclear forces. The North is suspected to be making strides on the development of the Hwasong-20 ICBM, which was first revealed this month. Analysts suggest that it is being manufactured in part due to technological assistance provided by Russia. Kim Sang-woo, a former politician with the left-leaning South Korean Congress for New Politics and now a member of the board of the Kim Dae-jung Peace Foundation, said that the Iron Mace and Freedom Edge drills are critical in reinforcing the alliance between Seoul and Washington. "Former [South Korean] President Yoon Suk Yeol went to Camp David with US President Joe Biden and Japanese Prime Minister Fumio Kishida in August 2023, they agreed on the creation of a nuclear consultative group, which was the US guarantee to increase its nuclear umbrella when North Korea became more aggressive and its capabilities were enhanced," he told DW. "The agreement at Camp David was the counterbalance to the North and in part it was meant to try to reassure the South that it did not need to develop its own nuclear capabilities because the US would protect it," he added. Hundreds arrested in US immigration raid on Hyundai plant