Thousands of military leaders and business executives will gather in Paris next week for Eurosatory, one of the world's most important defense trade shows. However, the charm of a visit to "the city of lights" will be muted by worries over the potential terrorist attacks and anxieties over Britain's pending vote on whether to exit the European Union.

That the trade show timing coincides with Euro 2016, a huge global soccer tournament being held in Paris, serves as an eerie reminder of the Nov. 13 attacks that killed 130 people in the French capital city. That terrible night started with an explosion at a soccer match at the Stade de Paris. French leaders have promised the highest security precautions will be enforced for upcoming events, but certainly defense leaders planning to attend Eurosatory cannot help but believe that terrorists would see them as high-value targets.

While security forces may provide them safety and their presence help ease their nerves, nothing much can be done to soothe concerns about the June 23 referendum to be held across the English Channel, as British citizens go to the polls to decide whether the country remains a member of the 28-nation European Union.

The worries are legitimate. Opposition to of Britain's exit — "Brexit" — from the EU range from 10 Downing Street and around the globe to the White House. Defense experts, including former NATO officials and U.S. security officials, warn a decision to leave the EU would weaken security for the British and all of Europe.

And, many experts say, it will at the same time hurt trade, including the defense industry.

British Prime Minister David Cameron delivers a speech on "the future of the European Union and Britain's role within it." Cameron argues that withdrawing from the EU will hurt Britain's standing with the US.

Photo Credit: Ben Stansall/AFP/Getty Images

President Obama, at a joint appearance last month with British Prime Minister David Cameron, went so far as to say UK withdrawal from the EU would mean the "U.K. is going to be in the back of the queue" on trade deals with the US."

Obama said the US would of course consider a UK-US trade agreement, but noted the focus would be on negotiations with an agreement with a big bloc — the European Union.

Internally, exiting the EU, could spark spending cuts for the British military and require a new strategic defense and security review, according to a report by the deputy director-general of  the Royal United Services Institute think tank.

Those seeking to leave the EU are rallying on concerns about the surge of immigrants into Europe and in belief the economy would fare better as a fully independent nation.

Industry has been pushing back, warning that route would in fact harm the economy and Britain's standing in the world. A recent survey showed defense companies overwhelmingly favor staying in the EU. Airbus leaders sent letters to employees that highlighted the advantages of the status quo.

Both sides of the Brexit debate cite numbers to bolster their cases. But an impressive roster of global economic and political leaders line up on the side of the UK remaining in the union. And the US and EU economies are close rivals, meaning the European countries as a group have greater leverage in trade and security than do standalone nations.

Until the advocates for breaking away can make a more convincing argument of the advantages of leaving the EU, staying put remains the wiser course.

More In Intercepts