For the second time in one week, Japan's foreign ministry has had to lodge an international complaint after a neighboring military power got a little too close for comfort. This time it was Russian fighter jets that allegedly breached Japanese airspace and spurred Japan into sending its own fighter jets into the air to chase them off.  "Defence ministry official Yoshihide Yoshida told journalists it was not clear whether the incursion by two Su-27 aircraft was intentional or accidental, but described it as 'extremely problematic'," reports the BBC.  

It's problematic because Japan and Russia still haven't buried the hatchet over a set of disputed islands which Russia refers to as the Kuril Islands and are known in Japan as the Northern Territories. And it just so happens that Thursday was "Northern Territories Day" reports Reuters.  So obviously Russian jets encroaching on Japan airspace on Northern Territories Day was enough to set Japan off. 

This disruption just comes two days after Japanese officials announced that a Chinese navy frigate targeted one of their ships with weapons-locking radar. Though jets were not involved in that incident, it did occur in the East China Sea where China and Japan are fighting over a different set of islands. 

"Roman Martov, a Far East regional spokesman for the Russian air force, was quoted by Russian media as saying the planes did not enter Japanese airspace." reports the BBC.