According to South Korea’s military, North Korea fired artillery pieces into waters off the coast of North Korea on Sunday. This was days after North Korea’s latest missile launch failed amid the country’s recent surge in weapons testing activities.

Rumours abound that North Korea may soon launch its long-range ballistic missile, a developmental long-range ballistic missile. This would increase its arsenal and put pressure on the United States to make concessions in negotiations still in limbo. South Korea’s military suggests that North Korea’s last Wednesday midair missile explosion involved parts from the Hwasong-17 missile. This is its largest weapon.

South Korea’s Defense Ministry reported that it had detected firings from several rocket launch systems near the west coast of North Korea on Sunday. According to the ministry, the military monitors North Korean movements closely and is ready for any eventuality.

Separately, the South Korean presidential office stated that it had called for an emergency meeting of its national security council to discuss “short-range missile launches” by North Korea.

It said that members of the Council worked closely with the United States to examine details of the firings. It stated that South Korea will leverage its military capabilities and alliance with the U.S. in order to prevent any security vacuums from forming during a period of power transition in Seoul.

Moon Jae-in’s five-year-old term expires in May. He will be replaced by Yoon Suk Yool, a conservative government. Yoon, a former top prosecutor has pledged to strengthen Seoul’s military alliance and Washington’s security commitment to counter growing North Korean nuclear threats.

Wednesday’s failed missile firing by North Korea was the 10th weapon launch of this year. According to the U.S. military and South Korean militaries, two North Korean launches prior Wednesday’s were intended to test a Hwasong-17-based system. Later, North Korea claimed that the launches were intended to test cameras and other systems in order to spy satellites.

According to some experts, North Korea is likely to launch a Hwasong-17 rocket in order to test its long-range missile technology as well as to place its first operational spy satellite into orbit. The Hwasong-17 could reach a maximum range of 15,000 km (9,320 miles), and its large size means it can carry more payloads or nuclear warheads.

If successful, the Hwasong-17 launch would be the North’s most serious provocation since 2017, when the country conducted three intercontinental missile test.

South Korea’s government did not immediately reveal the location of Sunday’s weapons-firings. There were naval clashes at the Koreas’ western sea border, which was not clearly marked, in 1999 2002 and 2009. In 2010, 50 South Koreans were killed in an attack blamed on North Korea. There were 46 deaths on a warship, and four on a border Island.