U.S. must beware

Inevitability arrived at the airport in Brussels and visited its subway for Tuesday’s morning rush hour, this time in the shape of three bombs. Dozens were killed and many more injured.

The initial bulletins from Belgium, horrific as they were, were at the same time not unexpected. Carnage on such a scale still shocks the senses, but such terrorism is nothing new to Europe.

Just this week French anti-terrorism authorities released a 55-page report detailing what they knew, what they’ve learned, and what they still do not know about the terrible Islamic State attacks Nov. 13 in Paris. Coordinated shootings, bombings and hostage-takings left 130 dead and the world aghast.

Now, the hometown of the last known survivor of the Paris attacks explodes into a state of emergency.

Two bombs ripped through Brussels’ Zaventem airport – one from a suicide bomber in the departures area – and another at the entrance to the Maelbeek subway station in the heart of the city, near the European Union headquarters.

If Paris destroyed our hopes that the Islamic State could be contained to its home base in Syria and Iraq, Brussels should convince us that determined, networked terrorists remain a step ahead of those chasing them.

The Islamic State, in fact, has been losing ground at home, with Russian and U.S. bombing helping to chip away at its held territory by as much as a fifth, by some experts’ estimates. Those experts also warn that this only accentuates Islamic State leaders’ resolve to take the fight into Western nations.

Whether or not Salah Abdeslam was involved, the Brussels attacks – barring the coincidence of all coincidences – were a clear message.

Like his compatriots, Abdeslam managed to travel freely in Europe, easily evading police who pursued him from Paris to return to Brussels. The French report on the Paris attacks noted that Islamic State operatives exploited weaknesses in European border controls to move about undetected. They also worked with a high-quality forger in Belgium to acquire false documents, The New York Times reported.

Authorities have been surprised to learn the size and scope of the terror network in Europe and now must assume that the Islamic State has other webs operating. Officials concede that they cannot track all of the Europeans traveling to and from Syria and Iraq, as many of the Paris attackers had.

This is a serious problem for Europe, but it’s not solely Europe’s problem. Make no mistake that a deadly attack on U.S. soil is the ultimate prize for Islamic State leaders. Consider Chattanooga, Tenn., San Bernardino, Calif., and Garland, Texas, fair warning.

As Europe has learned, such skirmishes are not the end of anything.