North Korea fired two short-range ballistic missiles towards the East Sea on Monday, the second attack within 48 hours and a day after US-South Korea staged joint air drills, Yonhap News Agency reported.

South Korea’s Joint Chiefs of Staff (JCS) said they had detected the launch from North Korea’s Sukchon area between 7 am to 7:11 am. “While strengthening its monitoring and vigilance, our military is maintaining a full readiness posture in close cooperation with the US,” the JCS said in a text message sent to reporters.

This comes a day after the US and South Korea staged combined air drills, involving at least one B-1B strategic bomber, on Sunday, Seoul’s military said.

During the drills, F-35A stealth fighters and F-15K jets from the South flew together with US F-16 fighters to escort the B-1B aircraft entering the South’s air defence identification zone, according to the Joint Chiefs of Staff (JCS), reported Yonhap News Agency.

US and South Korea launched its drill after North Korea confirmed that they had fired ICBM on February 18 in a “surprise launching drill.”

The training this time demonstrated the South Korea-U.S. combined defence capabilities and posture featuring the alliance’s overwhelming forces, through the timely and immediate deployment of the U.S.’ extended deterrence assets to the Korean Peninsula,” the JCS said in a press release.

It added that the air drills affirmed Washington’s “ironclad” commitment to the defence of the peninsula and its extended deterrence pledge.

Monday’s launch marks the North’s third missile provocation this year, according to Yonhap News Agency.

Kim Yo-jong, the influential sister of North Korean leader Kim Jong-un, issued another sharp-tongued threat of “corresponding” actions against the allies’ military drills.

“The frequency of using the Pacific as our firing range depends upon the U.S.,” she said in an English-language statement carried by the North’s official Korean Central News Agency.

The latest sabre-rattling raised concerns that the North may continue to engage in such provocations as the allies plan to hold a tabletop military exercise against North Korean nuclear threats this week and their springtime Freedom Shield exercise next month, as per the report in Yonhap News Agency.