The governments of Japan and China signed their Treaty of Peace and Friendship four decades ago, on Aug. 12, 1978. The bilateral accord came into force on Oct. 23 that year.

The treaty expresses hope for contributions to peace and stability in Asia and in the world based on peace and friendship between the two countries.

Over the past four decades, Tokyo and Beijing have deepened economic ties and human exchanges, but have experienced a slowdown and deterioration of their political relationship due to tensions over historic perceptions and national security policies.

The treaty was introduced six years after the normalization of bilateral ties in 1972. It drastically changed the international order in Asia under the Cold War between the United States and the Soviet Union.

Negotiation of the treaty was difficult, but differences were overcome, largely due to diplomatic efforts by Japanese lawmakers.

In the ruling Liberal Democratic Party (LDP), those who were opposed to the treaty and sympathetic toward Taiwan, which China regards as a renegade province, had the upper hand, and then Prime Minister Takeo Fukuda, who was promoting an “omnidirectional foreign policy,” lacked wiggle room because of his considerations for the Soviet Union’s stance.

These circumstances prompted pro-Beijing LDP lawmakers, members of the suprapartisan Japan-China Friendship Parliamentarians’ Union, and senior Komeito officials to engage in shuttle diplomacy to gauge the Chinese side’s position.

Back then, Japan’s diplomatic stance toward China was apparently still being formed. But the active exchanges joined not only by politicians but also by business figures resulted in a wide array of human connections.

The bilateral relationship worsened after Japan nationalized the disputed Senkaku Islands in 2012. The relationship has since improved but is merely returning to a “normal orbit,” as Chinese Premier Li Keqiang has stated.

The political relationship between the two countries remains deadlocked because of the thorny issues of the Senkaku Islands and Taiwan, as well as China’s maritime advances and Japanese politicians’ visits to the controversial Yasukuni Shrine.

Now Prime Minister Shinzo Abe is scheduled to visit China in October, and Chinese President Xi Jinping is envisioned to visit Japan for the first time in June next year. It is possible that President Xi will make a state visit and meet with the new Emperor.

It is important to strengthen ties through mutual visits by top officials. But the thinning out of human connections between Tokyo and Beijing due to the retirement of Japanese politicians close to China remains a concern. A similar situation exists with regard to Japan’s bilateral ties with the United States and South Korea.

The Abe administration has let Japan’s relationships with neighbors such as China and South Korea decline, but has spared the U.S. administration of President Donald Trump of strong criticism over his country’s strengthening of its nuclear arsenal and protectionist trade policies.

The Cabinet is responsible for foreign policy. Excessive intervention in diplomatic affairs by lawmakers would cause problems. But at the same time, the Diet has a responsibility to monitor the administration’s execution of foreign policy through the ratification of treaties and other means.

Multilayered diplomacy complementing the government’s foreign policy is needed to solve deep-rooted problems and develop international relations.