Lots of BS on this thread. @
senheiser 's graphic shows the ENTIRE Russian Navy, rather than just the Pacific Fleet. The US is hardly a "whole gang", it's one country. As depicted below, most US forces are not in the west pacific regularly.
Anyhow... what I could find:
Russia Pacific Fleet:
1 cruiser
5 destroyers
4 SSBN
5 SSGN
4 SSN
7 SSK
Japan: (total, divide by two if you assume they preserve half the force for possible Southern threats, or make up your own percentages)
4 "helicopter cruisers"
24 destroyers
13 frigates
16 SS (all diesel)
US pacific fleet (again, should be divided to account for multiple zones of coverage, also need to account for the US Navy being pretty damn quiet about where their subs actually are located)
7th Fleet (western pacific, based in Japan)
1 CVN
2 CG
7 DG
1 LHD (the assault ships that are standard sized carriers with helo, harriers, and Marines)
3 SSN (based in Guam)
3rd fleet (eastern pacific, including alaska, west coast of North America, basically east of the international dateline, but you gotta figure there'd be some quick transfers in case of hostilities)
4 Carrier strike groups, variable composition, 1 CVN + typically 4-5 surface combatants and 1 SSN
difficult to say where other US subs are - there are more, but... they don't talk much about where they are assigned.
Another consideration is that realistically, not all these ships (from any country) are available all the time. They are capable of operating maybe 30% of the time on a peacetime footing, maybe 50% on a wartime footing(?). Some countries are not as good at keeping ships out at sea as others, but I couldn't give you numbers on that.
China has apparently put forces into the N. Pacific, but probably not regularly, and it wouldn't make much sense if they were teaming with Russia. You'd want to keep the forces closer to home, under land-based air cover, and draw off US/Japanese/Korean strength from a northern fight. I suspect North Korea is too politically unreliable to be of use to anyone, and South Korea probably not interested in fighting on behalf of Japan while North Korea is un-engaged (if ever).