China and Japan held their first formal security discussions in four years, with Chinese officials concerned about Tokyo's military expansion and Japanese diplomats criticizing Beijing's strong ties with Russia and alleged deployment of spy balloons.

The discussions, intended at reducing tensions, began on Wednesday in Japan's capital.

Japan announced in December that it will double defense spending over the next five years to 2% of GDP, or $320 billion. Meanwhile, it also boosts its alliance with the US creating deeper Chinese concerns that Japan will not hold up its commitment to peaceful development.

Tokyo intends to obtain longer-range missiles capable of striking mainland China and to stockpile additional weaponry required to maintain a battle alongside the big US army it hosts.

At the outset of the meeting in Tokyo with Japanese Deputy Minister of Foreign Affairs Shigeo Yamada, Chinese Vice Foreign Minister Sun Weidong said, "The international security situation has undergone vast changes and we are seeing the return of unilateralism, protectionism, and a Cold War mentality." 

He also warned against Japan's "negative moves" toward Taiwan, which he said were made in collaboration with powers outside the area.

On his part, Japan's Deputy Foreign Minister Shigeo Yamada expressed worry about the two countries' territorial dispute over uninhabited islands in the East China Sea, known as the Senkaku in Japan and the Diaoyu in China.

The Diaoyu Islands are the subject of expanded territorial claims from China and Japan. China cites Japanese maps from 1783 and 1785 that show the islands as being in Chinese territory, whereas Japan argues that its rule over the islands has been in place since 1895. The Diaoyu Islands came under the US administration following World War II before being transferred to Japan in 1972.

Japan is of the opinion that China's claims to sovereignty over the islands stem from the 1970s discovery of lucrative minerals in their shelf waters. When the Japanese government acquired three of the five islands from a private owner in 2012, the territorial issue intensified.

At the end of the meeting, Sun highlighted that they had also discussed Japan's release of wastewater from the destroyed Fukushima nuclear reactor into the Pacific, as well as "unblocking" industry supply networks. He didn't go into specifics.

China is Japan's most important trading partner, accounting for around one-fifth of its exports and nearly a quarter of its imports. It is also a significant manufacturing base for Japanese firms.

After the US downed a suspected Chinese spy balloon, Japan announced last week that it will clarify military engagement rules to allow its jet fighters to shoot down unmanned aircraft that violate its airspace.

Following the meeting, Japan's Foreign Ministry issued a statement emphasizing the importance of peace and stability in the Taiwan Strait.

The two countries had agreed to create a direct contact hotline "around spring" and to boost dialogue between their senior security officials.

The talks come at a crucial time when the US is exerting strained efforts to push East Asian countries to get ready for a fight. For the US, China is a threat. For Japan, China will always be the neighbor next door and a key trade partner.