And Europe will join in because....?
With newly acquired airpower, Iran is likely to prompt or provoke or amplify a proxy war or Mideast war that will endanger Europe’s interests — including their desire not to suffer a renewed flood of refugees. To press that and other arguments, the US can deploy considerable economic and political threats and incentives, including trade terms and US military basing and troop levels. And the US can warn that in a crunch, the US will back Israel against Iran with little consideration as to Europe’s desires and interests.