Originally Posted by WillTravel4Food

JFK MCT Int'l to Int'l is 2 hours. It won't matter which airline combination you pick if the connection time is less than that. If you book on separate tickets, then you will need to assume the risk that you won't make the connection. At JFK, this is not something I'd consider. If anything, I'd be looking at getting a connection time somewhere around 4 hours.

PS: I had to look this one up. Nexus allows expedited US entry from pre-cleared Canadian airports only. Entry into the US from Japan is not eligible for Nexus.