That's a good point! Russia stationed ships in New York Harbor?
Yes, they were worried about a war with someone else, and they did not want to get trapped in Baltic/Black Sea. The war never came. It is part of the reason Russia would eventually sell Alaska. It was selling to an ally.
And BTW, it is what is left out of Turtledove Great War series. If the CSA won the civil war, the USA would enter the alliance system as Russia ally, and early on. So the entire alliance picture he portrays would probably not exists. For example, the USA could easily end up as an associated power of the three emperor's league if that still comes to pass. And with the USA/Russia alliance, Japan will act a lot differently. Instead of his simple add USA to Central Powers, but only after war in 1880's and CSA to Entente, I think you see the world move more towards three alliance standard. Russia/USA. Japan/UK to counter, since both could have issues with a joint war with the USA/Russia. Japan on the naval side. The UK would be looking at fighting the USA in Canada and the Caribbean while Russia would be viewed as a threat to India. Splendid Isolationism will end much earlier than OTL for the UK out of necessity. The if the Austrian-German war occurs like OTL (far from given), we will see a third axis of AH/Germany. Turtledove scenario is a longshot at best, mostly because he conveniently ignores one fact. The USA is not going to stay isolationist for the 1880's war. If you see a rematch in this time frame, I would gamble we see a great war a generation earlier than OTL. Not to mention he skips over the likely hood the USA has a reserve system based on France/Germany, so we can likely mobilize 2.4 million men (10% of total population). And even if 1 million men, it forces the UK to keep a large standing army. Not to mention the Indian wars in the USA are over by 1870. We throw a 100K men at the problem if needed, not 5K or so from OTL. It is not Custard regiment attacking the Sioux, it is the Custard Corp. The Sioux wars might last only one year. Same for Apache, whenever we get around it. It is why people talk so much about butterflies on the board. With a major POD like changing who wins a war, the world looks nothing like OTL within a few years.