The bombings in Brussels this morning feel like a watershed moment in the history of what we can no longer deny is a war. In Paris they attacked Europe’s social life and its values as a collection of western democracies. France, and to a lesser degree, Belgium had to respond but neither were significantly disrupted. The attacks on Brussels airport and its metro system are another matter altogether. They differ from the Paris attacks not in the heart wrenching pain and anger they cause, but in the nature of the target and in the response they demand.

In Brussels they attacked the transportation system. Not just any transportation system but the one at the heart of institutional Europe and indeed, at the core of its fundamental freedom. In doing so, the enemy has also disrupted Europe’s governance, its political alliances, and the economic structures that underpin it. NATO, the European Union, the European Parliament, and many others all revolve around Brussels. These must be defended and we urge Europe’s leaders in the coming days to consider difficult decisions about the use of European power with wisdom and foresight but also with stoicism and boldness.

There will be many questions and intense differences about the proper response but leaders must resist the urge to consider national solutions. In the run up to this tragedy there have been too many fractures resulting from pressure. The refugee crisis, Russian adventurism, and the financial collapse of the southern states, were all met with national responses. To do so again at this moment will doom the European experiment because none of the member states possess the financial or military power to defend it alone. Whatever the outcome, Europe must coalesce around a course of action or face the dire consequences of disunity.

The impacts go far beyond the continent.  America needs Europe to be stable and secure.   The United States must not “lead from behind”, fail to live up to its defense commitments, or ignore another red line. These are the reasons the situation in the Middle East is spreading into European cities in the first place. Like Europe, America must also be bold and stoic. It is time to face the fact that neither money nor airstrikes will solve the problem nor can it be ignored.

Lino Miani is a retired US Army Special Forces officer, author of The Sulu Arms Market, and CEO of Navisio Global LLC