The United States and South Korea have staged a series of dramatic bombing drills designed to send a message to Kim Jong-un.
The flurry of military drills comes after Pyongyang fired another mid-range ballistic missile over Japan last Friday.
They also follow North Korea's sixth and most powerful nuclear test on September 3 which was in direct defiance of United Nations sanctions and other international pressure.
South Korea's defence ministry said a pair of US B-1B bombers and four F-35 jets flew from Guam and Japan and joined four South Korean F-15K fighters in the latest drill.
The joint drills were being conducted "two to three times a month these days", Defence Minister Song Young-moo told a parliamentary hearing yesterday.
Meanwhile, Russia and China have staged naval exercises ahead of a UN General Assembly meeting where North Korea's nuclear ambition is likely to dominate proceedings.
According to Russian news agency TASS, the drills aimed to "consolidate partnership and practical co-operation between the two militaries" and were not aimed at any one country.
Russia and China claim the drills are not directly related to the current crisis engulfing the Korean Peninsula.
Beijing's official Xinhua news agency confirmed China and Russia began naval drills off the Russian far eastern port of Vladivostok, not far from the Russia-North Korea border.
Those drills were being conducted between Peter the Great Bay, near Vladivostok, and the southern part of the Sea of Okhotsk, to the north of Japan, it said.
'READY FOR WAR'
Russia and China's joint war games in the North Pacific form an eight day program of joint land and sea drills which include defending ships from an air or naval attack.
The two countries do not have a formal military alliance, but according to the Wall Street Journal are developing common techniques which will allow them to train and fight together.
Vasily Kashin, a military expert and China specialist at the Higher School of Economics, told the WSJ the nations were building a "de facto" alliance.
Arseny Sivitsky, director of the Belarus-based Center for Strategic and Foreign Policy Studies, indicated Russia was sending a message to the West.
"Russia is trying to show Europe and the United States that it is ready for a full-scale war and that is why we should all sit down and talk about geopolitics on Russia's terms," he said.
World leaders have converged on New York for the UN General Assembly however Russian leader Vladimir Putin has stayed for the military exercises known as Zapad.
This wouldn't be the first time the powerhouses have joined forces, as Russia and China have been conducting joint military exercises for more than a decade.
The latest drills are the second part of China-Russian naval exercises this year, the first part of which was staged in the Baltic in July.
The area has been a spot of inflamed tensions between Russia and the West, however both Moscow and Beijing insisted at the time the drills were not directed at any particular country, the New York Times reported.
According to Xinhua, the Russia-China drills are expected to wind up on September 26.
'RUNNING OUT OF OPTIONS'
Both Russia and China have condemned North Korea's ballistic missile and nuclear tests, with Beijing calling them "regrettable."
Washington has been pushing China to do more to rein in its neighbour and ally, while Beijing has urged the US to refrain from making threats against the North.
In a recent press conference Putin urged all parties to stop escalating tensions, warning of catastrophic consequences if conflict broke out on the Korean Peninsula.
On Sunday, US Ambassador to the United Nations Nikki Haley warned the UN Security Council had run out of options on containing North Korea's nuclear program.
She also said the US might have to turn the matter over to the Pentagon.
In response, Chinese Foreign Ministry spokesman Lu Kang said the most pressing task was for all parties to enforce the latest UN resolutions on North Korea fully, rather than "deliberately complicating the issue".
US President Donald Trump has vowed that North Korea will never be able to threaten the United States with a nuclear-tipped ballistic missile.
Asked about Mr Trump's warning last month that the North Korean threat to the US would be met with "fire and fury", Ms Haley said: "It was not an empty threat."
Pyongyang has launched dozens of missiles as it accelerates a weapons program designed to provide the ability to target the US with a powerful, nuclear-tipped missile.
It says such programs are needed as a deterrent against invasion by the US, which has 28,500 troops stationed in South Korea.
South Korea is technically still at war with North Korea because the 1950-53 Korean conflict ended with an armistice and not a peace treaty.