(Bloomberg) -- North Korea says it tested four missiles this week to boost deterrence against its foes and pledged to keep developing more powerful warheads, a state media report said, as Pyongyang continues to fire off one of the biggest barrages since Kim Jong Un took power a decade ago.

The first of two tests this week aimed to update the country’s long-range cruise missile system and sent two long-range cruise missiles to hit an island 1,800 kilometers (1,119 miles) away, the official Korean Central News Agency said Friday morning. 

A second test on Thursday saw Pyongyang launch two guided missiles to “confirm” its ability to fire conventional warheads with surface-to-surface tactical guided missiles, and also hit a target island, KCNA reported. 

“The practical combat performance of the long-range cruise missile system would hold a reliable share in boosting the war deterrence of the country,” KCNA said, noting that the “missile warhead institute” of North Korea’s Academy of Defence Science “will keep developing powerful warheads capable of performing combat function and mission.”

Pyongyang has ramped up tensions with six separate weapons tests this month that were capable of striking U.S. allies South Korea and Japan. It also fired two “hypersonic missiles” designed to use high speeds and maneuverability to evade U.S.-operated interceptors, as well as conducted its second test of a system to launch ballistic missiles from train cars.

Kim’s regime has warned the Biden administration it might end its almost five-year halt on tests of nuclear devices and long-range missiles to deliver them to the U.S. mainland.

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