On Monday, Kim Jong Un‘s North Korea accused U.S. spy planes of violating its air space and threatened to shoot them down, escalating tensions ahead of the NATO leaders’ annual summit this week in Lithuania.

What Happened: North Korea’s Defense Ministry spokesman accused the US of “the most undisguised nuclear blackmail” by planning to bring a nuclear-armed submarine to the peninsula and conducting “hostile espionage activities” by flying spy planes off its east and west coasts, Bloomberg reports.

North Korea claimed that drones and spy planes flew for eight straight days along its coasts, with aircraft violating its airspace. The spokesman warned that there is no guarantee that such a shocking accident as downing of the US Air Force strategic reconnaissance plane will not happen.

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Pyongyang has threatened to take actions to prevent Washington's "reckless acts."

Kim Jong Un's regime has previously fired off ballistic missiles shortly after making threats. Last month, it launched two short-range nuclear-capable rockets just minutes after KCNA issued a dispatch from a Defense Ministry spokesman denouncing joint US-South Korean military exercises and threatening retaliation.

Why It Matters: The latest threats from North Korea come as South Korean President Yoon Suk Yeol attends the North Atlantic Treaty Organization Summit. Yoon has stated that he will seek help from NATO leaders on how to deter Pyongyang from increasing its atomic ambitions. This development follows a series of aggressive actions and threats from North Korea, including calls for a "war of revenge" against the US and vows for a more aggressive response to US military measures on the Korean peninsula.

North Korea has fired off more than 90 ballistic missiles over the past 18 months as Kim rolls out new weapons to deliver a nuclear attack on the US mainland and America's key allies in the region, South Korea and Japan.

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