Short of actually sending a lens to Nikon for evaluation, there is only ONE sure way to tell if it is USA Warranty, and that is if the seller has its original warranty card that has the lenses matching serial number on it.

Nikon bodies are much easier as the first two digits of the bodies serial number will tell you what worldwide market they were imported to. SOME of Nikon's lenses actually use"US" preceding their serial number, but by no means does not saying "US" tell you the lens was grey market.

ALL Nikon USA Warranted bodies will have serial numbers starting with 25XXXXX through 39XXXXX. Any numbers starting with any other digits were never properly imported for sale in the USA and Nikon will not work on them directly. HOWEVER, Nikon does authorize Nikon APPROVED repair centers to work on many grey market items AND Nikon original parts are made available for those repair centers without penalty or limitations. Most of the products on that authorized gray market repair list are no longer in production by Nikon. Parts for items still in production are NOT provided by Nikon for gray market versions under any circumstances, so any parts for them need to be sourced from the open market with no assurance they are not counterfeit.

I will be faced with this ban since I'll be flying from Haifa to Philadelphia on Turkish Airlines with a changeover in Istanbul. So, foreign carrier (one of the best, by the way) and banned airport. I will have two Fuji X-T2's with me, two lenses, and a Nikon flash. No problem taking the cameras over with me, but a problem taking them back with me. There is no way that I will be touring the pyramids, Karnak, Wadi Rum, and Petra and not be taking my cameras. Shipping them back is prohibitively expensive to say nothing of the complications with US Customs. Now I have to buy a Pelican case, two Pelican cable locks, and make sure that the equipment is listed on my floater insurance policy. I have to ask the insurance company how to prove that the cameras were stolen out of checked luggage, as they are almost certainly to be.

This ban has nothing to do with security. It is to overcome the financial advantage the foreign carriers have over the American carriers. Thank you, Mr. Trump.