- Dec 2018
Do you mean Japan wanted control of Vladivostok? As far as Russia goes, Vladivostok is not ice free but can be kept open most winters with ice breakers now, but I'm not sure about at that time. Port Arthur (Lüshunkou) on the Yellow Sea was leased to Russia by China and was considered a warm water port.
There are two different things in this discussion:
1. What Russian Empire needs on Far East for their geopolitics:
The answer is : a) all-year-around (not frozen) port and naval base in region; b) Free (controllable) access to Pacific; c)Manchuria (and probably Korea, which appears in the list later) with resources;
2. What high rank Russian officials and financial groups (incl. Tzar's family) wanted in this region. This is include a) all Korean and Northern China resources (more than Manchuria only); b) open trade port, connected with mainland by railway, for access to SE Asia market.
From geopolitical point of view selection of Port Arthur in Liaodong Peninsula was a mistake - this was not suitable for main naval base for many reasons. However, it was sufficient (if consider it together with the port Dalnii /Dalyan and built railway) for support interests of Russian financial groups on Far East.
Any ports inside Sea of Japan (even not-frozen) cannot be considered as open and accessible to Pacific.
From geopolitical point of view, the best location for naval base for Russians could be a Korean ports (Busan/Chemulpo?). But this was totally unacceptable for Japan.
Japan also have geopolitical needs and good wishes of politics/financial groups. And access to Korea was in their geopolitical agenda. But Vladivostok in that period was in wish list only.
Would Japan have agreed to a north-south partition of Korea with Russia in the absence of war?
However Est-West subdivision (along peninsula ) may be suitable for both Empires : Busan can be Russian, and Chemulpo- to Japan. But both parties does not looks for compromises, militarists groups want a "small successful war" on both sides.
The result is well known.