If you want to be extra careful, put a label on the UPS in your checked luggage noting that it contains a "nonspillable" battery (use that word) in case it is opened for inspection.

When carrying such a battery in carry on luggage, I have had a TSA x-ray operator get all testy and ask me if the battery contained "liquid." He clearly was hoping to have found a Big Catch (TM) and an excuse to confiscate my battery. My answer repeatedly used the terms nonspillable, absorbed-glass-mat (AGM), and no liquid, and he quit bugging me.