Upvote:4
As a general rule, all passengers arriving into (or even transiting through) the US are required to clear immigration and customs at their first point of arrival to the US. Having done this, they will be left land-side in the airport - at least in part because as a part of clearing customs they will have had access to their luggage, so could have taken items out of their luggage that are not allowed through security.
In order to continue on to a connecting flight, they will need to re-check their checked luggage (if any), and then pass through security (TSA).
However, there is one main exceptions to this general rule.
That exception is "Pre-Clearance", which is a process where passengers pass through US immigration and customs at their departure airport. On arrival in the US, these passengers are treated the same way that domestic passengers would be in that they are let out air-side, and would not need to re-clear security unless (for example) they needed to move to a different terminal which was not connected airside to the terminal they arrived in (specifically for JFK, most terminals are NOT connected air-side in any way).
The full list of pre-clearance departure airports is on the site linked above, but basically includes most (major) airports in Canada, a few in the Caribbean, Dublin and Shannon in Ireland, and Abu Dhabi in the UAE. Most (but not necessarily all) passengers from these airports will go through the pre-clearance facility before departure.
Upvote:7
Yes, you have to undergo TSA screening. There's no way to avoid this because some items that are allowed in checked luggage are forbidden in the cabin. Knives come to mind as an example. The only way to be sure that a traveler hasn't removed such an item from the checked luggage is to screen the traveler.
As noted elsewhere, there is likely to be a dedicated checkpoint for transferring passengers with shorter wait times.
I also note that this holds for travelers who have not checked luggage. The only way to avoid it would be to have dedicated passport and customs clearance for travelers without checked bags, and I am unaware of such facilities anywhere.