However, North Korea's recent cooperation with Moscow increased. Last month, North Korea thanked Russia for using its veto of the UN Security Council to appoint a panel of experts to monitor the regime's international sanctions.
Olympic organisers have issued a "deep apology" after South Korea's athletes were mistakenly introduced as North Korea at the opening ceremony in Paris.
North Korea reportedly sent 10,000 troops to support Russia in October, with initial weeks spent in training and support roles. The alliance between Russia and North Korea has strengthened in recent months.
No fewer than 18 people have died as multiple wildfires rage across South Korea's southeastern region, with thousands of firefighters aided by the military deployed in a bid to contain one of the country's worst forest fires in decades.
Against a backdrop of military posturing from Kim Jong-un's North Korea, the new bomb was shown at Seoul Air Base as part of a ceremony marking the 76th anniversary of South Korea's military.
South Korea and the United States said on Monday that they would stage the Ulchi Freedom Guardian summer exercises on Aug. 21-31 to improve their ability to respond to North Korea's evolving nuclear and missile threats.
UK Foreign Secretary David Lammy said "To keep fighting in Ukraine, Russia has become increasingly reliant on North Korea for troops and weapons in exchange for oil."