Russia Reportedly Deploying Missile Systems on to the Kuril Islands

This is why the Russians hurried to seize the Kuril Islands after World War II and have refused to give them back, it is all about keeping the Sea of Okhotsk a giant Russian lake:

A Russian government source said the document obtained by Kyodo News was drawn up sometime after this summer. It remains unknown whether the plan was approved by Putin. Russian media recently reported on the envisioned military buildup in the area.
By setting up a defense line around the islands in the Sea of Okhotsk, Russia is aiming to keep foreign vessels out of the waters where its nuclear submarines are deployed, while also securing the free navigation of the Russian Pacific Fleet, which is headquartered in Vladivostok.
According to the document, new shore-to-ship missiles systems called the Bastion, with a range of more than 300 kilometers (over 180 miles), and the Bal, with a range of over 130 km (over 80 miles), will be deployed on six islands and on the Kamchatka Peninsula.
Missile systems were deployed in 2016 on Etorofu and Kunashiri, two of the four islands and islets off Hokkaido that are claimed by Japan.

Japan Times

You can read more at the link.