US strikes on Iran expose limits of Trump’s burden-sharing defense strategy, according to testimony from a senior Pentagon official who acknowledged that recent military operations do not fully align with the administration’s stated goal of pushing allies to take on more responsibility for their own security.
The issue took center stage during a Senate Armed Services Committee hearing, where Elbridge Colby, the Undersecretary of Defense for Policy, was questioned by lawmakers from both parties about the Trump administration’s National Defense Strategy and how the strikes against Iran fit within that framework.
Colby told senators that encouraging allies and partners to shoulder a greater share of collective defense remains a central principle of US policy. However, he stressed that the strategy was never intended to restrict Washington’s ability to act when it perceives a direct threat.
“We obviously want allies and partners to take general responsibility for their own defense,” Colby said during the hearing on Tuesday. He described burden-sharing as a broad theme rather than a rigid rule, adding that the strategy is “not a kind of straitjacket.”
He clarified that references to “primary responsibility” in the National Defense Strategy are aimed mainly at specific regions, particularly Europe and South Korea, where the US believes local allies have the capacity to take a stronger leadership role.
Although the hearing was formally focused on the National Defense Strategy, it also became the first public opportunity for lawmakers to question a senior administration official about the US and Israeli strikes on Iran. The military action has raised concerns in Congress about whether Washington is drifting away from its stated goal of reducing direct involvement in overseas conflicts.
As senators pressed Colby on the administration’s claim that Iran posed an imminent threat, he repeatedly pointed to a classified briefing scheduled for later that day. That response frustrated several lawmakers, who argued that Congress and the public deserve clearer explanations when large-scale military operations are undertaken.
Senator Jack Reed, the committee’s top Democrat, said the National Defense Strategy appeared outdated only months after its release in January.
“The most fundamental problem with this strategy is that it bears no resemblance to what this administration is actually doing,” Reed said. He noted that while the document emphasizes empowering regional partners, the United States has just carried out what he described as its largest military campaign since the 2003 invasion of Iraq.
When asked directly about the rationale for the strikes on Iran, Colby referred to public statements made earlier in the week by Defense Secretary Pete Hegseth and Chairman of the Joint Chiefs of Staff Dan Caine. He said the operation was intended to limit Iran’s ability to project military power against the US and its allies.
Reed responded by quoting language from the strategy itself, which says the Pentagon will “empower regional allies and partners to take primary responsibility for deterring and defending against Iran and its proxies.” He argued that the recent strikes appeared to contradict that commitment.
Democratic Senator Elizabeth Warren also challenged the administration’s position, accusing it of embracing policies it claims to reject. She said the operation against Iran echoed past approaches marked by interventionism, prolonged conflicts and regime-change ambitions.
Colby rejected that characterization, arguing that the strikes were narrowly focused and designed to serve US national interests. He said the operation should not be confused with humanitarian interventions or open-ended military campaigns aimed at reshaping other countries.
Republicans on the committee largely defended the administration’s actions. Senator Markwayne Mullin said Iran posed a serious and immediate threat, praising the president’s willingness to act decisively. Senator Dan Sullivan urged Democrats to recognize what he described as the longstanding danger posed by Iran, arguing that deterrence requires strength.
Beyond the debate over Iran, lawmakers from both parties raised broader concerns about the National Defense Strategy itself. Committee Chairman Roger Wicker criticized what he sees as an underestimation of threats from China, Russia and North Korea.
Referring to the war in Ukraine as Vladimir Putin’s “ruthless war of choice,” Wicker said the US should not expect European allies to manage the response on their own. He argued that American leadership remains essential in confronting major global challenges.
Colby responded that the strategy reflects what he called a realistic assessment of global threats, particularly those involving nuclear-armed adversaries. He said his recent travel to Europe, South Korea and Alaska showed that allies are increasingly prepared to take on greater responsibility.
According to Colby, European nations are “leaning into” the idea of playing a larger role in countering Russia, even as the US continues to provide support and coordination. He framed the approach as a return to traditional alliance principles rather than a retreat from leadership.
“This is a return to the Cold War mentality,” Colby said, referring to a period when alliances were built around shared responsibilities rather than unilateral action. “We’re going back to that heritage.”
The exchange highlighted a persistent tension within US defense policy. On one hand, the administration wants to reduce America’s global burden and encourage allies to step up. On the other, crises such as Iran test how far Washington is willing to step back when it believes its own security is at risk.
Critics argue that repeated US interventions undermine the credibility of burden-sharing efforts, signaling to allies that Washington will ultimately act regardless of their contributions. Supporters counter that deterrence depends on the willingness to use force when necessary, especially against adversaries seen as unpredictable.
As conflicts continue to simmer across the Middle East, Europe and Asia, the challenge for the Trump administration will be translating its strategic vision into consistent policy. For now, US strikes on Iran expose limits of Trump’s burden-sharing defense strategy, raising questions about how the United States balances restraint, leadership and responsibility in an increasingly unstable world.
