Let me give the verse in question in a slightly larger context.
1 Thessalonians 5:1-3 But of the times and the seasons, brethren, ye have no need that I write unto you. For yourselves know perfectly that the day of the Lord so cometh as a thief in the night. For when they shall say, Peace and safety; then sudden destruction cometh upon them, as travail upon a woman with child; and they shall not escape.
One of the common teachings of scripture is that the Lord will come as a thief in the night. That is, He does not announce His coming; He will not call us up to tell us He will be arriving in a few minutes; He does not give us an absolute sign to announce His soon arrival. I find it interesting that a passage where Paul is teaching the inability to predict the coming of the Lord is being used to teach necessary signs before He returns.
The point being made in this passage is that the day of the Lord will come unexpectedly. Just when people think He will never show up and they do not have to worry about His arrival; suddenly, He will appear! Verse three does not say that it must be at a time of compete peace and safety. It just tells us that this will be the emphasis in the lives of people. This world cannot have fullness of peace and safety until Jesus sits as King in Jerusalem. Up to that time, we are just kidding ourselves.
However, if you want a demonstration that this time could be today, I challenge you to carefully watch the evening news for about a week. Watch both local and world news. Notice how many times they report on peace initiatives or interview people who talk about wanting peace. Notice also how many times safety comes up. It could be safety from a terrorist attack or safety by means of a product recall. I am sure that you will find that much of what this world says today is, Peace and safety. "For when they shall say, Peace and safety; then sudden destruction cometh upon them, as travail upon a woman with child; and they shall not escape." They are saying, Peace and safety. The Lord could come at any time.