The JW answer was that it prophesied the resurrection of deceased anointed ones in 1918, all at once. However, they never addressed verse 17 with any finality which says "Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord."
They did offer that it 'could' be that the annointed still alive prior to Armageddon could be taken to heaven all at once, but they waffled back and forth as to when this might occur. While saying that all anointed would share in the battle of Armageddon as brothers of Christ, they later said that some could live through Armageddon and be taken afterward. Clearly, they have no insight on the matter, per their usual 'make it up as they go' method of muddling through scriptural explanations.
I recall some 'heavies' saying that that 1 Thess sounded like Christendom's version of the rapture, but they did not want to use the word. Typical WTC spin.
WTC also uses these verses as proof that Jesus is Michael the archangel.
I always found it puzzling that they claimed that the Kingdom was established in 1914, but had no officials other than Christ until 1918. Details, details - don't bother Watchtower with details.