If there’s anything we can learn from the carnage in Brussels, it’s that countries all over the world have failed to implement the necessary security measures to stop terrorism on a mass scale. Obviously, no country can prevent every single attack, but what terrorists inflicted in Paris and Brussels is no easy feat.

One of the questions raised in Brussels is similar to what Americans were asking after Boston, Chattanooga and San Bernardino: How were these terrorists, some of whom were known radicals, able to carry out these attacks at an airport during high alert?

Here’s something else to ponder. The only thing between these terrorists and American soil was a plane flight. And if they felt so inclined, there was virtually nothing stopping them from hitching a ride here. The Investor’s Business Daily editorial board writes:

> “Belgium is one of 38 countries we let participate in the Visa Waiver Program. Its citizens and permanent residents don’t need a visa to travel here, allowing them to bypass standard security measures for visitors. Belgium now supplies the highest per-capita number of fighters to the Islamic State of any European nation, and most of them are Belgian nationals. That means they would be able to travel to the U.S. with a visa waiver.”

There are things we can — no, must — do to mitigate the chances of terrorists arriving here. We can start by amending a policy that allows Islamofascists to fly unvetted into the United States to inflict similar atrocities.