But history teaches us that such an approach is a strategic dead end, and recalling the past reminds us that every time we have gone in an isolationist direction, the result has been calamitous for the entire world.

Whether we like it or not, the security and prosperity of both our countries cannot be separated from the political and economic conditions on the continent. There is simply no retreat from this reality. The connections are too considerable – and too consequential.

Some have suggested that leaving the EU would reduce the risk of terrorism in the UK. That is mistaken. The terrorist threat, unfortunately, will be with all of us for the foreseeable future, as the recent events in Belgium have just shown. In fact, the best way to defend ourselves is precisely by deepening military, intelligence, and diplomatic cooperation across the Western world, by working together with our partners on the continent and elsewhere to strike at the terrorists in their sanctuaries and tackle the underlying drivers of radicalization. The EU, for all its imperfections, is a vital player in this effort.