CHITOSE Japan - The number of times Japanese fighter jets scrambled to ward off Russian military aircraft more than doubled in the last six months, amid diplomatic tensions between the two countries which Prime Minister Shinzo Abe is keen to ease.
The increased activity in Japan's north also comes as the armed forces pivot their focus southwards towards China, the assertive Asian giant which is seen in Tokyo as the more immediate challenge.
According to government figures released this week, instances of fighter jets scrambling into the skies above Japan jumped by 73 per cent in the six months through September, led by sorties confronting Russian bombers and spy planes.
Scrambles jumped to 533 from 308 a year earlier, the Defence Ministry said, and the total is on course to surpass figures seen during the last fiscal year, themselves the highest in nearly a quarter of a century.
Flights dispatched specifically to meet Russian aircraft in the latest six months soared to 324 from 136, although they eased during the second half of the period under review.
"We don't know the reason for the increased air activity. That's something for the Russians to answer," said a Self-Defence Forces official, who declined to be identified under ground rules for a recent press tour of facilities in Hokkaido.
The official would not discuss the circumstances surrounding the surge in scrambles against Russia.
The Russian Defence Ministry failed to answer repeated telephone calls made by Reuters on Wednesday for comment.
Hokkaido is a Japanese island to the north of the country's main land mass, and it lies close to four smaller islands which are claimed both by Japan and Russia.
The territorial dispute has prevented Japan and Russia from concluding a formal peace treaty and helps explain Japan's north-facing military posture, with mechanized infantry divisions and tank brigades set up to repel a feared Soviet invasion.
Besides economic and energy ties, Abe's diplomacy aims at resolving the dispute over the islands that Moscow seized in the final days of World War Two.
That task is being complicated by Japan's decision to join Western sanctions against Moscow for its annexation of the Crimea peninsula in March and its involvement in a pro-Russian rebellion in eastern Ukraine.
Moscow denies sending troops and arms to the area.
However, Tokyo's measures against Russia have been lighter than those of the United States or the European Union.
Abe said on Wednesday he hoped to meet Russian President Vladimir Putin at an Asia-Europe summit this week, and the two are expected to meet at a Pacific Rim gathering next month.