Chinese and Russian bombers took part in a joint patrol over the western Pacific on Tuesday, a day after the two countries were hit with fresh sanctions from the United States , but sparking concern in South Korea and Japan . The four Chinese H-6Ks and two Russian Tu-95s flew together over the Sea of Japan – also known as the East Sea – and the East China Sea in an exercise that was part of an annual programme of military cooperation, China’s defence ministry said. On Monday, the US announced new curbs on Chinese and Russian companies – many of them in the aviation sector – buying American technology. According to Beijing, Chinese Foreign Minister Wang Yi told his Russian counterpart, Sergey Lavrov, on Tuesday that the two neighbours should seek to “maintain stable relations in a chaotic world”. “The United States continues to wield the big stick of unilateral sanctions, which will only makes its record in the world more disgraceful,” his ministry quoted him as saying. Despite the show of solidarity, the exercise rang alarm bells in Seoul and Tokyo, as the six bombers entered the air defence identification zone around the South Korea-controlled Dokdo islands, a small group of islets that are also claimed by Japan. Tokyo responded by scrambling fighter jets to monitor the Chinese and Russian planes, its defence ministry said. Beijing, however, said the warplanes had not entered South Korean airspace and had acted in accordance with international aviation rules. “During the training, Chinese and Russian warplanes strictly abided by international law and did not enter the airspace of South Korea,” foreign ministry spokesman Zhao Lijian said. Tuesday’s exercise was a repeat of a similar drill conducted by Chinese and Russian bombers in the same region in July last year. Xi Jinping tells Russia, Asian partners to oppose interference by ‘external forces’ Russian President Vladimir Putin said in October that there was currently no need for a military alliance between the two neighbours, but said one could be forged in the future. Tian Shichen, a retired Chinese navy captain and director of the Centre for International Law of Military Operations in Beijing, said the joint patrol would help build the partnership between China and Russia but it was unlikely the two would form a military alliance. “I don’t think China has changed its stance on forming military alliances with other countries,” he said.