The presidential office Cheong Wa Dae on Wednesday convened a National Security Council session over North Korea's firing of short-range ballistic missiles.

Earlier in the day, the North fired two ballistic missiles off its east coast, according to South Korea's Joint Chiefs of Staff.

They flew some 250 kilometers, marking the second such launch in less than a week.

Chung Eui-yong, the national security adviser, presided over the meeting of the NSC standing committee, according to Cheong Wa Dae.

"At an emergency NSC meeting, North Korea's missile launches and the current security situation will be discussed," Ko Min-jung, presidential spokesperson, told a press briefing.

"Intelligence authorities of South Korea and the United States are analyzing (details about the firing)," she said. "The South Korean military is monitoring the situation and maintaining its (defense) posture."

President Moon Jae-in is receiving real-time reports from the military. His office is operating an emergency response mode.

On Thursday, the North fired two short-range ballistic missiles from the same area into the East Sea in its first launch since May.

The missiles, presumed to be the North's version of Russia's Iskander, flew some 600 kilometers.

North Korea said last week its firing was a "solemn warning" against South Korea over Seoul's planned joint military drills with the US and its purchase of US fighter jets. (Yonhap)