Interesting video discussion the implication of H-6N with air launched DF-17.
Assumptions: being air launched, the ALBM DF-17 gains additional range due to starting from altitude and at velocity, as well as having a first stage nozzle optimised for atmosphere-vacuum pressure range rather than surface-vacuum pressure range. The assumption is that ALBM DF-17 has 3000km range.
Assumption: H-6N, with aerial refuelling would have up to 6,000 km tactical radius.
Note he mentions the H-6N armed PLAAF formation is larger than other bomber formations, and their base may have facilities associated with nuclear weapons.
He calculates range from an origin point right in the middle of China in Henan:
Honolulu: 8,800km
Anchorage: 7,000km
San Francisco: 10,000km
New York or Washington DC: 11,000km
Paris or London: 8,500km
Based on this, the most likely target for this combination is Hawaii. However, if a certain "friendly" nation where to offer refuelling and right of way an attack over the north pole against mainland US would be possible. Although an attack against New York or Washington would mean the H-6N must reach launch position in Canadian airspace, an attack on San Francisco would require a launch position near Alaska. These positions are heavily monitored and defended by NORAD so is not very likely to be successful for an non-stealth aircraft like H-6N.
For attack on Hawaii, H-6N must penetrate the area near Japan and Taiwan which means JASDF, USAF based in Japan and ROCAF need to be suppressed. Although one imagines in a situation where attack on Hawaii (particularly if a nuclear one) is called for than all bases in the first island chain would already be out of commission from PLARF missile attack.
Once H-6N is over the Pacific Ocean undetected it would be extremely difficult to stop this attack. Any carriers that might be in the area to attempt an intercept would already have been targeted by AsBM from either land based PLARF DF-26B, or other H-6N carrying ALAsBM. For aircraft based in Hawaii, it would be very hard for them to locate and sortie out an aircraft to intercept H-6N 3,000km out. Once a DF-17 is launched its of course nearly impossible to intercept with existing missile defence.
If Russia where to coordinate with China on this attack so that H-6N can be aerial refuelled in Russian airspace then penetrate into the Pacific Ocean via Sea of Okhotsk then this attack would be much easier.
It's not known if DF-17 can be used to attack a ship underway at sea. Chances are at this time it can't, but there's no reason to assume a future anti-ship version of DF-17 wouldn't become available. H-20 would also make this kind of attack much easier to execute.