Tokyo, Jan. 23 (Jiji Press) — The number of scrambles conducted by Japanese Self-Defense Forces fighter jets against Chinese intelligence-gathering aircraft that flew across the Tsushima Strait stood at six, a record high, in April-December 2018, Japan’s Defense Ministry said Wednesday.

The previous all-time high for the nine-month period was two, in April-December 2016, according to the ministry. The strait lies between the Kyushu southwestern main island of Japan and the Korean Peninsula.

The ministry is increasingly alert as Chinese warplanes are believed to be expanding their areas of operations.

In April-December last year, the SDF scrambled its fighters against foreign aircraft that threatened to violate Japanese airspace a total of 758 times, up from 736 times in the same period of 2017 and the second-highest level on record for the nine-month period.

Of the total, 476 scrambles, or 63 pct, were conducted against Chinese planes, up by 81 year on year.

Meanwhile, 270 were in response to Russian planes, down by 58. Many of the planes were found flying over the Sea of Japan or around the northernmost Japan prefecture of Hokkaido, according to the ministry.