I received links to two different pages
featuring a series of pictures showing what is described as a 'monster' and an 'unknown creature'.
On one of the sites, this description is given:
This creature was found by Russian soldiers on Sakhalin shoreline. Sakhalin area is situated near to Japan, it’s the most eastern part of Russia, almost 5000 miles to East from Moscow (Russia is huge). People don’t know who is it. According to the bones and teeth - it is not a fish. According to its skeleton - it’s not a crocodile or alligator. It has a skin with hair or fur. It has been said that it was taken by Russian special services for in-depth studies, and we are lucky that people who encountered it first made those photos before it was brought away.
Ignoring the unverified description, I'm fairly sure it's a beluga whale
A site describes them as: "... a small white whale measuring 9 to 15 feet in length
(Seems about right, sizewise). Belugas are found throughout the Arctic Ocean and in a few other isolated populations. Belugas were once heavily hunted for their meat, hide (for leather) and oil.
(Thanks to Sarah and Gerrit for the links, and Charybdis for his excellent googling skills.)