Last month, a group of seven U.S. generals and admirals—including the top admiral in charge of U.S. military operations in the Asia-Pacific region—prepared to travel to the Aspen Security Forum, in Colorado. Security officials had spoken at the annual conference for years, including during Donald Trump’s first term, and were set to discuss topics such as the wars in Gaza and Ukraine, the future of AI, and threats from China. But a day before the forum began, the officers’ staff got calls from the Pentagon telling them to stay away. On social media, Sean Parnell, the Defense Department’s top spokesperson, later made clear why: The forum, he said, was “hosted by an organization that promotes the evils of globalism, disdain for America, and hatred for our great president, Donald J. Trump.”
Aspen, it turned out, was only the beginning. Within days, Defense Secretary Pete Hegseth had ordered the DOD to vet all future event attendance by any defense official. In a statement to Politico, Parnell declared that the move was meant to “ensure the Department of Defense is not lending its name and credibility to organizations, forums, and events that run counter to the values of this administration.” (The Aspen Institute, which sponsors the security forum, describes itself as nonpartisan.)
Parnell’s characterization of the new policy was vague, but it represented an abrupt departure from long-established DOD practices, and an important shift in the way that the military engages with the outside world: A Pentagon that has already grown more insular under Hegseth could end up cutting itself off from thinkers and ideas beyond the building, or at least those with which the administration disagrees.
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Military personnel and conference planners I spoke with described the decision as the latest battle in a broader war on ideas at the Pentagon under Hegseth. Earlier this year, the DOD eliminated the Office of Net Assessment, which had been created in the 1970s as a hub for strategic analysts to produce internal assessments of U.S. readiness against potential foes. Hegseth, who himself keeps a small group of advisers, was behind both decisions, defense officials told me.
Troops and civilians attend hundreds of events annually on behalf of the Pentagon, and have been doing so for decades. Whether gatherings on heady topics such as economic warfare and “gray zone” tactics or highly technical symposia about combatting rust on ships and the future of drone warfare, these events keep the military plugged into ideas from scholars and industry. Particularly since the Iraq War, the military has said that it wants to seek out ways to challenge its assumptions and solicit outside views—to make officers think through their plans and strategies and the second- and third-order effects of their decisions. Conferences are some of the main venues for this kind of exchange, though not the only ones; officers from dozens of other nations sit alongside American counterparts at U.S. war colleges, for example.
Previous administrations have required military personnel to secure approval to attend conferences. The difference, this time, is the apparently partisan slant to the vetting process. By prohibiting DOD personnel from engaging with viewpoints that the administration disagrees with, defense officials and conference planners told me, the Pentagon risks groupthink that could have real consequences.
Pete Mansoor, a retired Army colonel who served as executive officer to General David Petraeus during the 2007 surge in Iraq, told me he believes that Hegseth’s emphasis on “lethality” over the kind of strategic thinking often fostered at conferences and think tanks could prove dangerous. “The fact that officers stopped thinking strategically and only thought about lethality resulted in a war that was almost lost in Iraq,” Mansoor, now a senior faculty fellow at Ohio State University’s Mershon Center for International Security Studies, said. “I’m sure the Russian army also stresses lethality,” he continued, “but they have educated their generals on the basis of a million casualties” in Ukraine.
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If the department continues to ban conference attendance in a substantial way, it will also make U.S. forces more like their Russian and Chinese counterparts, which in many cases can seek outside views only through state-sanctioned academics. “When did our ideas become so fragile that they can’t stand up to someone who has alternate views?” one defense official asked me. (The official requested anonymity because they were not authorized to speak publicly about this issue.)
The Defense Department review of conference attendance is having an immediate impact. Only after the policy was announced did Pentagon officials realize how many conferences military personnel attend, leading to a scramble to draft formal guidance across the force, defense officials told me. A DOD spokesperson was unable to tell me when such guidance will be released, and responded to a request for comment by pointing me to Parnell’s statement about the review. In the meantime, military personnel are preemptively canceling their attendance at conferences. Some inside the Pentagon have even canceled internal meetings, fearful of running afoul of the new ban on “events” and “forums” not approved beforehand. National-security experts at think tanks, which often host security conferences, told me they are now unsure how much they can engage with American service members and the civilians working alongside them.
Also unclear is whether the policy applies to industry-related conferences, some of which are sponsored by private companies that spend millions of dollars to host them. Adding to the confusion, it was not initially clear whether the policy applied to one of the services, the Coast Guard, which falls under the Department of Homeland Security, not the DOD; a Coast Guard spokesperson told me that the service is working to align its policy with current DOD guidance.
Some military leaders dislike attending conferences and think-tank events, of course. Appearing in public forums can mean facing political questions and potentially giving a career-ending answer. Moreover, some leaders argue, think tanks are not always the best source of new ideas, particularly given that so many of their staff members once worked in government themselves. To tackle national-security threats, generals and admirals should be focused on warfare, not speaking to those who have never been on the front lines, the argument goes.
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But the U.S. military has had a symbiotic relationship with think tanks for years. While government employees and military officers are mired in day-to-day operations and focused on tactical warfare, outside scholars have the time and space for engaging in strategic thinking and coming up with solutions to thorny problems. Some think tanks have created positions for serving officers, and the Pentagon has also created internal positions for think tankers, in part to facilitate an exchange of ideas. “So often in government, you are choosing between awful options. You think you have found the least-bad options, and places like think tanks allow you to test that conclusion,” Mara Karlin, a former U.S. assistant secretary of defense for strategy, plans, and capabilities, told me.
Several real policy changes have emerged from that arrangement. Scholars at the American Enterprise Institute, a right-leaning think tank, produced a proposal that served as a blueprint for the 2007 surge in Iraq, at a time when the security situation in the country was deteriorating. A 2022 Center for Strategic and International Studies war-game exercise found that, in a hypothetical situation in which China invaded Taiwan, the United States would be in grave jeopardy in a matter of weeks—the Chinese could successfully sink an aircraft carrier, attack U.S. bases in the region, and bring down American fighter jets. The exercise spurred Pentagon officials to reassess the military planning for a potential conflict in the region.
American officials have also made important statements and announcements at security-focused conferences. In the days before Russia’s 2022 invasion of Ukraine, then–Vice President Kamala Harris appeared at the Munich Security Conference to outline U.S. fears of imminent war. Earlier this year, Vice President J. D. Vance also attended the Munich Security Conference, where he blasted American allies and cast doubt on the idea that the United States would remain Europe’s security guarantor. This year, Hegseth himself appeared at the International Institute for Strategic Studies’ Shangri-La Dialogue, in Singapore, where he outlined U.S. strategy to combat threats from China. (Breaking with long-standing military norms of nonpartisanship, Hegseth also spoke to young conservatives at Turning Point USA’s Student Action Summit last month.)
Later this year, the Ronald Reagan Presidential Library & Museum will host a major national-security conference that usually draws Cabinet secretaries, industry leaders, and America’s top generals and admirals. Several past defense secretaries have delivered the keynote speech. A phrase often invoked at the conference is peace through strength, which Reagan introduced into the modern lexicon during the 1980 presidential election, and which became a mantra of his administration’s defense policy. It has also become one of Hegseth’s favorite phrases for describing the military under Trump. And yet, by Hegseth’s own directive, no one knows whether he or the troops he urges to embrace that approach will be able to attend the conference that celebrates it.
*Illustration Sources: Marat Musabirov / Getty; Javier Zayas Photography / Getty; cveltri / Getty; Svetlana Ievleva / Getty.