It was the first statement from Pyongyang on the issue since US President Donald Trump and North Korean leader Kim Jong Un agreed at an impromptu meeting in the Demilitarized Zone to resume stalled denuclearisation talks.
"While efforts are underway to arrange working-level talks between North Korea and the US in the wake of the top-level meeting at Panmunjom, the US is planning the joint 19-2 Dong Maeng military exercise," an unnamed spokesperson of the foreign ministry said in comments carried by state news agency KCNA.
"If realised, it will affect the working-level talks."
North Korea will be watching the "next move by the US" before it decides how to proceed on the talks, the official added.
The US and South Korea are due to hold joint military exercises in August.
The drills, which infuriate Pyongyang, were scaled down to facilitate dialogue with the North after Trump's historic first summit with Kim in Singapore in June 2018.
Tuesday's warning came moments after KCNA released a statement from the same official blasting the planned drill, calling it "blatant pressure" on Pyongyang and a "violation of the spirit of the June 12 joint statement" signed in Singapore.
At their latest meeting last month, Kim and Trump shook hands over the concrete slabs dividing the Korean peninsula before the US leader took a few steps into Pyongyang's territory in the border village of Panmunjom, becoming the first US president ever to set foot on North Korean soil.
Washington has previously insisted on North Korea's complete denuclearisation as a condition for lifting punishing US sanctions.
Failure to reach an agreement over sanctions relief and what the North was willing to give in return led to the collapse of the leaders' second summit, which was held in February in Hanoi.
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© Agence France-Presse
