Japan's ambassador to China returned to Beijing on Monday, after he was summoned to Tokyo over the weekend for talks on the Diaoyu Islands. Japan's Foreign Minister has denied that Uichiro Niwa's brief recall to Tokyo was designed as a protest despite tension between China and Japan over the disputed islands continuing to grow.

The ambassador's recall to Tokyo raised a number of eyebrows. Many wondered if it was a protest at Chinese patrol boats entering waters near the Diaoyu islands. Others speculated whether the ambassador was getting reprimanded, for saying things the Japanese government didn’t want to hear.

On Sunday, after talks with summoned ambassador Uichiro Niwa, the Japanese Foreign Minister Koichiro Gemba denied both scenarios. What he did say was he'd once again instructed Ambassador Niwa to accurately convey Japan's position on the Diaoyu Islands dispute.It's the first time Niwa has been recalled to Tokyo since his appointment two years ago.

Last month, Niwa said he opposed the planned purchase of one of the Diaoyu Islands by Japan's government. His words angered some conservatives, prompting calls for his dismissal. According to Gemba, the ambassador briefed him on China's stance on the island dispute, along with the latest developments increasing tension between the two countries.

Future plans were also discussed. The squabble over the islands, located near rich fishing grounds and potentially large oil and gas reserves, threatens to damage relations between Asia's two biggest economies.

Last week, Chinese vessels twice entered waters near the islands, after the Japanese Prime Minister Yoshihiko Noda said the government could buy an island from its private owners, instead of allowing the governor of Tokyo to go ahead with a similar plan. Since the move was announced, China has toughened its stance on the issue.

At a meeting with Gemba in Phnom Penh last Wednesday, Chinese Foreign Minister Yang Jiechi reiterated that China has "indisputable sovereignty" over the islands.

Sino-Japan ties appear to be reaching a new level of strain, in the latest face-off on the Diaoyu Islands. But the two trading partners are making substantial efforts to avoid a return to the acrimony of 2010, when Japan detained the skipper of a Chinese trawler whose boat collided with Japanese patrol ships in the same waters.