Pyongyang, May 26 (KCNA) -- Kim Kang Il, vice-minister of National Defence of the Democratic People's Republic of Korea, made public the following press statement "National sovereignty, security and interests will be protected with strong power for self-defence" on May 25: Various air spying means of the U.S. and the ROK puppet air force are openly intensifying their hostile air espionage against the DPRK recently. 16 strategic reconnaissance planes of the U.S. Air Force, five RC-135s and eleven U-2Ss, were involved in air espionage against the DPRK from May 13 to 24. Notably, the U.S. Air Force mobilized three RC-135s from May 20 to 23. The U.S. and the ROK puppet air force are still seriously encroaching upon the sovereignty and security of the DPRK, conducting air espionage at the level beyond the wartime situation by repeatedly mobilizing reconnaissance drone RQ-4B and other reconnaissance aircraft almost without any time lag every day. Such hostile military espionage, together with various military drills, has become the root cause of ever-escalating regional military tensions. Recently, the ROK gets undisguised in its despicable psychological warfare by scattering leaflets and various dirty things near border areas of the DPRK. Scattering leaflets by use of balloons is a dangerous provocation that can be utilized for a specific military purpose. We have already clarified our stand on the dangerous farce of scattering things by balloons. The number of enemy's intrusion across our maritime border is also increasing. Various sorts of warships of the navy and the maritime police of the puppet ROK are frequently crossing our maritime border under such pretexts as mobile patrol. A dangerous consequence will be entailed by such frequent intrusion across our maritime border. We have never crossed the northern limit line touted by the ROK. We have already warned that we would take a necessary military measure to defend our sovereignty and security. We officially warn that we can never tolerate such continued encroachment on our maritime sovereignty and that we may exercise our self-defensive power on or under the water at any moment. If any incident occurs on the sea, the ROK will be held wholly accountable, for its violation of the maritime sovereignty of the DPRK in disregard of its warning. It is a choice made by us that if the ROK refuses to respect the maritime border declared by the DPRK, it should make the ROK afraid of crossing it. The supreme military leadership of the DPRK on May 24 instructed its army to take offensive action against the enemy's provocative encroachment upon the sovereignty of the DPRK. Tit-for-tat action will be also taken against frequent scattering of leaflets and other rubbish by the ROK near border areas. Mounds of wastepaper and filth will soon be scattered over the border areas and the interior of the ROK and it will directly experience how much effort is required to remove them. When our national sovereignty, security and interests are violated, we will take action immediately.