Now what do you do if you detect SLBM launch from somewhere in the Pacific Ocean? Who do you nuke?
So the answer for deterrence purposes is you don't need to nuke anyone right away, immediate response is only one layer of the onion when it comes to nuclear deterrence.
This doctrine is called "launch on warning". It hasn't been official US policy for 20 years[1]: In 1997, the Clinton administration changed the official policy away from launch on warning to one of retaliation after withstanding an initial first strike.
It's not like in a hypothetical scenario where Russia has launched hundreds of ICBMs at the US in a first strike scenario Trump (or any other president) is going to feel beholden to some promise Clinton made in the 90s.
The president has absolute power over when and how to launch nuclear weapons, and can do so at a moment's notice, as has been covered extensively in the media in the last year where people seemed shocked that the president had this power since they didn't like the new person in office, even though the power itself hasn't changed in more than half a century.
What I'm pointing out is that you've conflated two things. Just because one aspect of your deterrence is the ability to launch your land-based ICBMs within 30 minutes, that doesn't mean that the inability to do so (e.g. because you don't know who struck you) means that you're out of options.
Besides, there's no way someone could amass enough SLBMs in the Pacific to take out two aspects of the US's nuclear triad without the US knowing who owns those submarines.
With SLBMs you have other options. You can have your attack submarine shadowing enemy's ballistic missile submarine, or surface ASW ships patrolling the area that can detect the first launch and try to sink the ballistic missile submarine before it can launch its remaining missiles.
That's nobody's nuclear posture, it's just a subset of the posture of the US, Russia, China etc.
So Russia is probably the best choice.
IIRC both have about 60 subs and Russia is back at their post-1991 strength.
See the recent WaPo article about them mapping undersea cables.
Second observation: Wikipedia says "Range: 14,484km (9,000 miles) at 9 knots".
Great circle distance from Pyongyang to Lima is 10,100 miles. http://www.gcmap.com/mapui?P=ZKPY-SPJC&DU=mi . That direct route goes through Utah, so the ocean-only route will be longer.
Pyongyang to Lima via Hilo is 10,550 miles. http://www.gcmap.com/mapui?P=ZKPY-ITO-SPJC&DU=mi . That's not much longer. Still, it's a reminder that we're talking about a spot almost at the other side of the world from NK.
On the other hand, http://www.russianwarrior.com/STMMain.htm?1947vec_Romeo.htm&... says that the range at snorkel is "7,000 nautical miles at 5 knots" while on the surface it's "16,000 nautical miles at 10 knots". That's 8,000 and 18,000 miles, respectively. Which means about 3,000 miles on the surface (=visible by satellite) followed by the rest at snorkel depth. And a one-way trip.
If I were the US Navy, and saw a NK sub travel towards the Americas for thousands of miles, I think I would keep a close eye on it.
Third observation: The NK Sinpo class submarine appears to have been built to 1) replace the Romeo class subs, and 2) be armed with an KN-11 ballistic missile. See https://en.wikipedia.org/wiki/Pukkuksong-1 . The longest estimated range for that missile is 2,000-2,500 km . Then again, the submarine itself has an estimated range of only 2,800 km.
The GC distance from Lima to Brownsville, TX is almost 3,000 miles, so well further than NK's relatively small ballistic missile can manage from that gap in US satellite surveillance.
So even if a Romeo-class submarine weren't detected via sonar, and had the range to get to that gap, and were modified to support a submarine-launched ballistic missile, it doesn't seem like that missile could reach the US.
Or, to quote from the last Wikipedia link:
> The Korean People's Navy has no nuclear submarines, and no diesel-electric submarines equipped with air independent propulsion (AIP), so the launch submarine's range (and by extension the missile's) is limited and assuredly prevents it from threatening America's western seaboard.
> Given their submarines' insufficient power to outrun U.S. Navy nuclear attack submarines and lack of aerial and surface coverage to protect them out to long distances, they cannot venture far out to sea, ..
> ... because of its finite power capacity, the sub would have to surface or snorkel for air to recharge its batteries if it remains hiding for an extended period, making it vulnerable to anti-submarine warfare (ASW) efforts.
Support for the only active war on Europe.
Destabilization of EU, NATO, US elections.
---
Take a look at Russian TV and polls. The Russian government (TV propaganda) and people (Putin has 80+ approval) do not want to be friends. (Unless you are Syria, Iran or North Korea).
Would the metric of having invaded two sovereign nations in the last few years count?
Where formerly the right harboured the deepest suspicions of Russia, the liberals have taken over the position, probably as a scapegoat for political retreats.
Posts on HN such as yours and probably mine will turn gray-white fast since if you haven't sufficiently disavowed Goldstein then you are probably a collaborator.