The Japan Ministry of Defence has reportedly revealed that the number of sorties to intercept Chinese military aircraft has more than doubled in the first quarter of this year.
Japanese fighter jets were deployed nearly 571 times to interrupt Chinese intrusions in fiscal 2015, media sources reported.
The number of scrambles by Japanese aircraft was up 23% during the year ending 31 March, when compared to the previous year.
Japanese Self-Defence Forces Joint Staff public affairs head Kazuhiko Fukuda was quoted by media reporters as saying: "The numbers of scrambles alone do not tell the whole story, but we should recognise that the increase indicates a tougher security environment.
"China is modernising its air force and is clearly aiming to improve its air combat capability in faraway skies.
"Concrete activities based on those targets are reflected in these numbers."
According to Stars and Stripes, of the total 873 sorties in Japan, 288 were operated to target Russian intrusions in fiscal 2015.
During the previous fiscal year 2014, Japan dispatched jets 943 times, 473 of which targeted Russian incursions.
The relationship between Japan and China has been strained because of a dispute over a group of tiny islands in the East China Sea Reuters reported.