North Korea has revised its constitution to require the military to launch a retaliatory nuclear strike if leader Kim Jong-un is assassinated or incapacitated by a foreign adversary.The constitutional change comes after Iranian supreme leader Ali Khamenei and several of his close advisers were reportedly killed in strikes during the opening phase of the joint US-Israeli attacks on Tehran.The revision was adopted during the first session of the 15th Supreme People’s Assembly, which opened on March 22 in Pyongyang. The changes were disclosed on Thursday during a briefing by South Korea’s National Intelligence Service (NIS) to senior government officials, Telegraph reported.According to the NIS briefing, Kim continues to hold command over North Korea’s nuclear forces, but the constitutional amendment formally defines procedures for retaliatory action if he is killed or unable to lead.The revised Article 3 of the nuclear policy law states: “If the command-and-control system over the state’s nuclear forces is placed in danger by hostile forces’ attacks … a nuclear strike shall be launched automatically and immediately.”Professor Andrei Lankov, a Russian-born professor of history and international relations at Kookmin University in Seoul said the change reflects growing concerns in Pyongyang following recent developments in Iran.“This may have been policy before, but it has added emphasis now it has been enshrined in the constitution,” he said.“Iran was the wake-up call. North Korea saw the remarkable efficiency of the US-Israeli decapitation attacks, which immediately eliminated the greater part of the Iranian leadership, and they must now be terrified.”Experts believe carrying out a similar operation in North Korea would be far more difficult than in Iran because of the country’s isolation and strict security controls. North Korea’s borders remain largely sealed and foreign diplomats, aid workers and businesspeople allowed into the country are closely monitored, limiting opportunities for gathering intelligence.Reports have suggested that Israeli intelligence tracked Iranian leaders through hacked traffic cameras in Tehran, but such tactics would be difficult in Pyongyang because of its limited CCTV network and tightly controlled intranet system.Kim Jong-un is also known for maintaining tight personal security. He is constantly accompanied by bodyguards, avoids air travel and usually travels by heavily armoured train.Prof Lankov said Pyongyang’s main concern is likely to be satellite surveillance technology.“Their biggest fear is going to be information from satellite technology. And, on balance, their concerns are not unfounded as taking out the leadership at the outset of any conflict is likely to be decisive,” he said.He added that North Korea’s military remains loyal to the leadership and would likely carry out retaliatory orders in the event of an attack.“I see no likelihood of an attack coming from South Korea so any retaliation would be aimed at the United States,” Prof Lankov said.Meanwhile, North Korea is also preparing to deploy a new type of artillery system near its border with South Korea, according to state media reports released on Friday.The official Korean Central News Agency (KCNA) reported that Kim recently visited a munitions factory to inspect production of a ‘new-type 155-millimetre self-propelled gun-howitzer’.KCNA said the artillery system has a range exceeding 37 miles and will be deployed this year to long-range artillery units stationed along the border with South Korea.The new weapon could place central Seoul, located about 35 miles from the border, within striking distance, along with large parts of Gyeonggi province, South Korea’s most populous region and a major industrial hub.The howitzer will “provide significant changes and advantages to our military’s ground operations”, KCNA quoted Kim as saying.Despite recent peace overtures from the South Korean government, North Korea has continued to describe Seoul as its main adversary and recently removed longstanding references to Korean unification from its constitution.North and South Korea technically remain at war because the 1950-1953 Korean War ended in an armistice rather than a formal peace treaty.