Japan has lodged a strong protest with China after a Chinese warplane intruded into Japanese airspace on Monday.

Japanese Vice Foreign Minister Okano Masataka summoned the charge d'affaires ad interim at the Chinese Embassy in Tokyo to protest the first-ever confirmed intrusion by a Chinese warplane into Japan's airspace. Okano strongly demanded that China take measures to prevent a recurrence.

The Japanese foreign ministry's Asian and Oceanian Affairs Bureau Director-General Namazu Hiroyuki also lodged a protest when he met with Director-General of the Department of Asian Affairs of China's Foreign Ministry, Liu Jinsong, in Tokyo.

According to Japan's Defense Ministry, the Chinese Y-9 intelligence-gathering aircraft was inside Japan's airspace for about two minutes on Monday morning, when it was flying over waters southeast of the Danjo Islands that are part of the city of Goto in Nagasaki Prefecture.

A senior Japanese defense ministry official warned that this could be part of Beijing's efforts to threaten Japan's interests, both at sea and in the air. The official said there have been a number of intrusions by the Chinese navy and coast guard into Japan's territorial waters.

Some Japanese government officials said it is too early to conclude that China's latest action was intentional. The government said it will continue assessing the incident, while keeping an eye on Chinese actions.