It follows Russian Defense Minister Sergei Shoigu visiting North Korea for the 70th anniversary of the end of the Korean War and holding talks with Kim Jong Un.
North Korea fired multiple cruise missiles toward the Yellow Sea just two days after the United States and South Korea ended their 11-day joint drills.
North Korean leader Kim Jong Un has vowed to bolster his navy's combat readiness with nuclear capabilities as the United States, Japan, and South Korea began their trilateral ballistic missile defense drills.
South Korea's Ocean Ministry said on Aug. 27 that tests carried out on the country's seawater showed radiation levels remain below the World Health Organization (WHO) standards for drinking water.