North Korea’s state media has reported on Thursday that country to develop and test “special armaments” to destroy the new South Korea’s F-35 stealth fighter jets.

In a statement denouncing Seoul for its recent acquisition of a number of new stealth jets from the U.S., an unnamed policy director at the foreign ministry’s Institute for American Studies said the move would serve to heighten tensions on the peninsula.

“There is no room for doubt that the delivery of ‘F-35A’, which is also called an ‘invisible lethal weapon’, is aimed at securing military supremacy over the neighboring countries in the region and especially opening a ‘gate’ to invading the north in time of emergency on the Korean peninsula,” the statement said.

“We, on our part, have no other choice but to develop and test the special armaments to completely destroy the lethal weapons reinforced in south Korea.”, KCNA news agency reported, citing a government researcher.

In September 2014, South Korea announced a deal to procure 40 F-35 fighters in a Foreign Military Sale (FMS) deal worth about $6.1 billion. South Korea took delivery of its first two F-35 jets in March, with more slated to arrive this year.

The South Korean government didn’t immediately respond to the North’s statement. But arms procurement officials said the F-35 project would proceed as scheduled and that about 10 of the 40 jets were to be delivered by the end of this year.

“The plan to integrate F-35A fighters into the military force is proceeding without any difficulty, but we are not able to confirm the schedule of acquiring [the aircraft],” the South Korean official said.