The defense ministers of China and Japan agreed Wednesday that the two countries will work together to achieve North Korea's denuclearization amid growing tensions between Washington and Pyongyang.

The agreement comes as denuclearization talks have stalled, with North Korea warning that it will resume nuclear and intercontinental ballistic missile tests if dialogue with Washington fails to achieve a breakthrough by the end of the year.

(Japanese Defense Minister Taro Kono, left, and Chinese Defense Minister Gen. Wei Fenghe)[Courtesy of the Japanese Defense Ministry]

U.S. Special Envoy of North Korea Stephen Biegun has asserted that "the United States does not have a deadline."

While visiting Japan and South Korea this past week, Biegun added Beijing to his list of destinations in order "to discuss the need to maintain international unity on North Korea" with Chinese officials.

According to Japanese Defense Minister Taro Kono, he and his Chinese counterpart Gen. Wei Fengzhe agreed on the importance of fulfilling U.N. Security Council resolutions on North Korea.

As for bilateral security cooperation, the two sides agreed to work to boost mutual trust and strengthen communication amid growing Japanese concerns over China's increasing military assertiveness in the East and South China seas.

"We want to strengthen communication and boost mutual trust to build a constructive bilateral security relationship," Wei said at the start of the meeting.

While also expressing a desire to increase mutual trust, Kono made clear that there are still various concerns between the two countries including the East China Sea.

"We have strong concerns especially regarding Chinese vessels and airplanes in the sea and airspace surrounding the Senkaku Islands," Kono said.

This is the first visit by a Japanese defense chief to China since 2009, reflecting a recent thaw in bilateral ties that had previously grown frosty over wartime history and territory.

Kono told reporters in Tokyo on Tuesday that he plans to have a "frank discussion" over various security and defense issues with Wei.

Japan and China are seeking to soon open a hotline under the bilateral Maritime and Aerial Communication Mechanism launched in June last year. The plan is aimed at averting accidental clashes between Japan's Self-Defense Forces and the Chinese military at sea and in the air.

The two countries have yet to settle a dispute over the Japanese-controlled Senkaku Islands in the East China Sea, which Beijing claims and calls Diaoyu. Chinese vessels have entered Japanese territorial waters near the islets on numerous occasions.

During his last visit to Beijing in August as foreign minister, Kono told his then Chinese counterpart Wang Yi that "a real solution" is needed regarding the islets in order to deepen Sino-Japanese ties.

The Japanese government expects Kono's two-day visit to lay the groundwork for Prime Minister Shinzo Abe's planned three-day trip to China from Monday for a trilateral summit with Chinese Premier Li Keqiang and South Korean President Moon Jae In.

Meanwhile, Chinese President Xi Jinping is expected to make his first state visit to Japan next spring.

Some Japanese conservative lawmakers, however, have called on Abe not to invite Xi to Japan, as political unrest in Hong Kong has continued unabated and Beijing has shown no sign of acceding to demands by pro-democracy protesters.

Kono said he urged China to create a "good environment" for Xi's planned visit while also conveying that the current unrest in Hong Kong should be resolved through peaceful dialogue.