All Us forces anywhere in the world are covered under their nuclear umbrella. As far as tactical nuclear weapons are concerned they will certainly not advertise it. Look at the example of New Zealand which declared itself a nuclear arms free country. After its declaration US naval ships stopped visiting all New Zealand harbors amid a diplomatic row between those countries. 
If you look back at the Korean Armistice signed after the conflict it states clearly. "All foreign troop will have to leave to peninsula and al nuclear weapons have to be removed as well. That armistice was signed by the US, China, South- and North Korea as  well as others. "After this peace treaty negotiations would commence. Well the Chinese left but the US stayed and why were nuclear weapons mentioned in this context if they were not present in the first place