Sev Lich or Black Lake – Azerbaijan or Armenia?

Armenia and Azerbaijan have never delimited and demarked their common border after the break-up of the Soviet Union. Thus it is not surprising that in some parts the border is unclear or in dispute. On such case, which currently leads to tensions between the two, is Lake Sev Lich region. Armenia accuses Azerbaijan of having illegally advance into Armenian territory and encroaching its sovereignity:

Today Azerbaijan’s armed forces crossed the state border of the Republic of Armenia and advanced as far as 3.5 kilometers in that section. In fact, they are trying to surround and siege the Lake.

Prime Minister of the Republic of Armenia

It’s unclear where the Azerbaijani troops are exactly at this point but if one wants to know what the maps say, lets first look at Google:

We see that most of the lake(s) are on Armenian territory and some of the Northern part is in Azerbaijan.
Of course, Google maps are nice, but hardly authoritative on what the borders are.
So lets look at another source. One would think that old Soviet Maps would give us a clue what the borders were between the Armenian and Azerbaijanian SSR, and indeed we can find such maps online. Here’s the relevant one from the Russian General Staff (1975 updated 1985):

From what I am hearing, Azerbaijan seems to want to claim the whole area of the Lake, with which the Armenian side is obviously in disagreement.

We’ll see how this develops. Russia has offered to help in border delimitation and demarcation if both sides request it, but I am currently unaware whether both sides have done so or not.
In any case, this will go on for a while and from the rhetorics from Armenia, this might turn a hot conflict at any moment.