South Korea's military fires on border islands for the first time in 7 years as a North Korean missile fails and the balloon war rages on

• South Korea has resumed live-fire drills after seven years.
• South Korea previously paused the drills due to a 2018 military accord, which North Korea is accused of violating 3,600 times.

The South Korean military resumed live-fire drills on border islands Wednesday after a seven-year pause. The exercise follows a failed North Korean missile test and a flurry of other activity and comes as the two countries battle with balloons.

North Korea conducted a suspected hypersonic missile test Wednesday morning, but it is believed to have exploded in midair. The launch came as North Korea expresses frustration with the trilateral drills between the US, South Korea, and Japan, for which a US Navy aircraft carrier is present.

Not long after, South Korea restarted its own firing drills on the border islands of Yeonpyeong and Baengnyeong.

The South Korean Marine Corps told Yonhap News Agency the drills were "defensive" and noted that the military will work to enhance "firepower operations capabilities and the completeness of the military readiness posture through regular maritime firing exercises."

The South Korean drills involved multiple rocket launchers, anti-tank missiles, and K9 howitzers.

Earlier this month, South Korea suspended a 2018 inter-Korean military accord it signed with North Korea, which banned drills, among other activities, from occurring in specified areas, including the border islands. North Korea had violated the accord roughly 3,600 times prior to South Korea's suspension.

But now the drills are back. Earlier this month, a US supersonic B-1B Lancer bomber conducted the aircraft's first live-fire bombing run on the peninsula in seven years.

As North and South Korea engage in various military activities, they have also been escalating tensions with balloons.

Hundreds of balloons filled with trash, among other things, have been floating from North Korea toward South Korea since May, and in response, Seoul activists have been flying balloons with leaflets and speakers toward North Korea.

CNN's Mike Valerio, who got ahold of one of the balloons, said that the speakers have been playing an "anti-Kim Jong Un anthem." South Korean activists have a long history of sending anti-Pyongyang balloons into the North that have also carried money, thumb drives, and ChocoPie desserts.

There's also been high-level diplomatic activity lately. After North Korea and Russia signed a new agreement that aligned their strategic interests and established a mutual defense pact, South Korea signaled it was re-evaluating some of its current positions, including on sending weapons to Ukraine.

The North has been fueling Russia's war with its own shipments, while South Korea has offered its support indirectly. South Korea has, however, expressed dissatisfaction with closer ties between Russia and North Korea.

"The government clearly emphasizes that any cooperation that directly or indirectly helps North Korea increase its military power is a violation of UN Security Council resolutions and is subject to monitoring and sanctions by the international community," South Korea's presidential office said in a statement.