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 nation's armed forces pivot their focus southward toward China, the assertive Asian giant which is seen in Tokyo as the more immediate challenge.

Government figures released this week show instances of fighter jets scrambling into the skies above Japan jumped by 73 percent in the six months through September, led by sorties confronting Russian bombers and spy planes.