Twenty-five years after 9/11 made terrorism the organising idea of Western security, the world it produced is coming apart in unexpected ways. The charts below explore how the post-9/11 security order has evolved, with Trump pushing Europe to carry more of the military burden, American voters growing wearier of foreign wars, and terrorism itself losing its centrality in Western foreign policy.
The acceleration came after Russia’s full-scale invasion of Ukraine in 2022. Trump, who had been criticising NATO’s unequal burden-sharing since his first presidential campaign in 2016 has since turned that complaint into more of a threat. Last year, NATO agreed to a new 5%-of-GDP defence and security spending target by 2035. (See Chart 1)
During the 2024 campaign, he said he would “encourage [Russia] to do whatever the hell they want” to members that failed to spend enough on defence.
To be sure, the old enemy has not vanished. But jihadism is no longer at the forefront of Western foreign policy. But the war on terror, the guiding framework for U.S. foreign policy for the previous quarter century, will be.
The Uppsala Conflict Data Program (UCDP) defines a state-based armed conflict as fighting over government or territory in which at least one of the main parties is a state and the violence causes at least 25 battle-related deaths in a year. That makes it a useful lens for the post-9/11 era, which quickly spilled beyond terrorist attacks into wars involving governments, insurgencies and foreign armies. The Taliban is back in Kabul and Islamic State remains the world’s deadliest terrorist network as of 2025. The irony is that jihadism has lost its old grip on Western foreign policy just as arguments over Islam, migration and national identity have moved deeper into domestic politics on both sides of the Atlantic. (See Chart 3)
As Philip H Gordon, international relations scholar and former national security advisor to the US Vice President, puts it in a recent essay written for the Foreign Affairs Magazine, reviewing journalist Peter Bergen’s new book “All the Presidents’ Wars”, “when Americans mark the 25th anniversary of the 9/11 attacks this fall, the threat of Islamist terrorism will certainly not be gone.
