Soon after the Israeli-U.S. war in Iran began on Feb. 28, 2026, U.S. President Donald Trump called upon NATO allies to help support the effort. The response of European leaders was at first mixed. Some, like the United Kingdom, offering limited or qualified support. Others — chief among them Spain — refused to assist the U.S. at all.

NATO members’ opposition to getting involved with the conflict hardened further after the alliance decided to sit out the subsequent U.S. blockade of the Strait of Hormuz.

The extent of the division between Washington and other members is such that European leaders have quietly begun considering a plan B should Trump make good on his threats to pull out of NATO altogether.

As experts on foreign policy, overseas military bases and security cooperation, we believe that even though historical tensions within NATO are not new, the recent divisions nonetheless pose a major challenge for the long-term viability of the alliance, particularly in an increasingly fragile U.S.-led international order.

The divisions that preceded Iran

Beyond the recent disagreements over Iran, 2026 has also seen the possibility of conflict between NATO members themselves.

In January, long-standing Trump designs over Greenland seemed closer than ever, with the U.S. verbally, at least, suggesting it was prepared to use economic and military coercion to acquire the territory from Denmark, a NATO ally. Despite tensions having since subsided, Denmark has released unprecedented details about how it prepared to defend against military action by its longtime ally.

While the extent of the Trump-originated rifts are new, NATO member nations disagreeing – sometimes vociferously – is not.

In the 1960s and ‘70s, when the U.S. was embroiled in the Vietnam War, members of Congress called on NATO members to contribute more to their own defense. Those were demands that the first Trump administration would later repeat.

In 2003, the U.S. push to invade Iraq also divided NATO. While some members, like the U.K. and Poland, joined the U.S.-led coalition forces in Iraq, others, such as France and Germany, opposed the invasion. Turkey, another NATO member, notably denied the U.S. use of bases in its territory in the lead-up to the campaign.

The increasing tensions led the NATO secretary-general at the time, George Robertson of Britain, to downplay the growing divide and assure the world that NATO members still supported the United States.

NATO countries have even come close to war with each other in the past. Most notably, Turkey and Greece came to blows several times, usually over their still-unresolved territorial conflict over Cyprus in the Mediterranean.

NATO’s evolving mission

Reducing tensions among European nations was always part of the NATO project. With the two world wars driven in large part by French-German rivalry, reducing intra-alliance conflict was central to NATO’s purpose. The first secretary-general of NATO, Lord Lionel Hastings Ismay, famously described NATO as aimed at “keeping the Russians out, the Americans in and the Germans down.”

With the fall of the Soviet Union, one of NATO’s core pillars collapsed.

In the 1990s, the organization’s mission shifted from an anti-Russian defense pact to promoting European regional security. During this period, NATO took part in conflicts in the Balkans from 1992 to 1999. It still maintains a peacekeeping presence there.

In 2001, when launching its war against Afghanistan, the U.S. invoked Article V, NATO’s collective defense clause, for the first and, to date, only time. This led NATO member nations to become militarily active well beyond Europe’s borders, including operations in Pakistan, the coast of Africa, Libya and Iraq.

The 1990s and early 2000s also saw NATO expand to include several former Soviet republics, a move that Russia opposed as hostile to its interests. In fact, post-Cold War NATO expansion into East Europe has long been one of Russian President Vladimir Putin’s chief grievances against U.S. foreign policy in Europe.

The Russian invasions of Crimea in 2014 and Ukraine in 2022 led to a renewed focus on Russia and Europe’s eastern borders, with NATO member nations coordinating on sanctions and military aid in support of Ukraine’s government. The war also led to another round of expansion, with Finland joining the alliance in 2023 and Sweden in 2024.

Trump’s opposition to NATO

While NATO has grown and its mission focus has changed over time, the Trump administration’s call to action against Iran is not an obvious extension of the organization’s evolved focus.

The war is geographically removed from Europe, and Trump has largely been unsuccessful in making the case for why Iran posed an imminent threat to NATO nations. The United States’ motivations and war aims also remain unclear and have been prone to change.

European countries largely agree on issues like preventing Iran from pursuing an unlimited nuclear program. But they have long preferred diplomatic initiatives – like the 2015 nuclear accord deal with Iran brokered during the Obama Administration – to military strikes.

Part of the disconnect now is how the U.S. under Trump views multilateral institutions compared with his predecessors. While past U.S. presidents have viewed NATO as an extension of the United States’ global interests, they also tended to value the alliance as a whole, despite Washington not always getting its preferred outcomes from it. For Trump, it is far more transactional.

Indeed, the Trump administration has framed the lack of support from NATO nations as evidence of the alliance’s decreased utility to the U.S.

Secretary of State Marco Rubio recently echoed that position, questioning the use of the alliance after several NATO members refused to allow the U.S. to use their airspace to conduct military operations in Iran.

During his first term, Trump also openly questioned NATO’s purpose. And he has repeatedly pressured allies to increase their defense spending, suggesting that allies were cheating the U.S. by an overreliance on American military strength.

The specter of unintended consequences

Even before Trump’s threats during his second term, Europe had already decided to change course. After the invasion of Ukraine in 2022 and the increasing fragility of the United States’ involvement in NATO, European countries began increasing military spending; NATO allies have also set targets for further increases in the coming years.

Germany aims to increase its military personnel by 50% in the next 10 years, and it has created its first permanent military deployment abroad – in Lithuania – since World War II. France has likewise announced plans to expand its nuclear arsenal and use it for extended deterrence for the rest of Europe.

Ironically, more spending may increase the chance of tensions between the Trump administration and NATO members.

Over time, the U.S. has reaped some benefits when allies spend less on their own defense. That’s because the U.S. has historically provided security guarantees for countries in exchange for more say over their foreign policies – something scholars refer to as the security–autonomy trade-off.

However, as the U.S. moves further away from a shared vision with European countries and U.S. policy becomes more volatile, American security guarantees may be less reliable in the eyes of many Europeans. Increased European defense budgets will therefore mean NATO members have more opportunities to assert their preferences against those of the U.S.

A changing role for NATO?

The world for the past 80 years has been characterized largely by U.S. political and military dominance. While it is clear that that world is changing, it is less clear what will replace it.

But understanding NATO’s history and its possible paths forward can give us some clues as to what that world will look like. And contrary to Trump’s short-term aims in nudging NATO allies to rebuild their militaries, a more powerful Europe likely means less U.S. influence in the long term, not more.

Michael A. Allen has received funding from the Department of Defense's Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office.

Carla Martinez Machain has received funding from the Department of Defense's Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office.

Michael E. Flynn has received funding from the Department of Defense's Minerva Initiative, the US Army Research Laboratory, and the US Army Research Office.

The Department of Justice announced in March 2026 that it is suing Harvard University and the University of California, Los Angeles.

The lawsuits allege that both universities failed to adequately address antisemitism on campus, violating students’ civil rights.

These cases follow earlier efforts by the Trump administration in 2025 to block federal funding to several major universities. The Trump administration has also – largely unsuccessfully – pushed universities to sign agreements that would give the federal government greater oversight over their day-to-day operations.

In 2025, the Trump administration launched broad Title VI investigations into 60 colleges and universities. These investigations focused on whether schools had done enough to protect Jewish students from discrimination and harassment, particularly in the wake of the Oct. 7, 2023, attacks on Israel, the subsequent war in Gaza, and widespread protests across U.S. college campuses.

Many of those investigations continue. Title VI is part of the Civil Rights Act of 1964 and prohibits discrimination on the basis of race, color or national origin in any program that receives federal funding.

These federal investigations have prompted scientific researchers, among others, across higher education to ask whether the government can invoke claims of civil rights law violations to justify cutting off federal research funding that supports their labs and projects.

As a scholar of educational leadership and policy, I think it is helpful to place the Trump administration approach to higher education within a broader understanding of how courts have interpreted civil rights laws within the past few decades and the nuanced way the Supreme Court has found they apply to universities.

Supreme Court weighs in

In 1964, Congress passed the Civil Rights Act. This law banned discrimination based on race, color, religion, sex or national origin in employment, education and public places.

Congress then passed the Higher Education Act in 1965. This law significantly increased the federal government’s investment in colleges and universities. It also created the Pell Grant program – the first federally funded need-based financial aid program for undergraduate students.

In addition, the Higher Education Act spelled out that schools that receive federal funding need to comply with civil rights laws.

Leaders of Grove City College, a small nondenominational Christian college in rural Pennsylvania, were concerned that this law would bring unwanted government oversight.

At the time, the college did not accept any direct federal funding. But some of its students received Basic Educational Opportunity Grants. These grants helped undergraduate students pay for college. Unlike loans, these grants did not have to be repaid.

In 1975, the Department of Health, Education and Welfare asked all universities and colleges with students who received federal grants to agree to comply with Title IX, a 1972 law that prohibits discrimination based on someone’s sex.

In 1976, Grove City refused to sign on to this agreement. A legal back-and-forth ensued.

Grove City College argued that the federal government’s request amounted to unwarranted government intervention, because the college did not directly receive federal funding. The Department of Health, Education and Welfare threatened to cut off the federal grants Grove City students received.

The Supreme Court eventually ruled in 1984 that Grove City’s financial aid program – but not the entire college – needed to comply with Title IX in order to receive federal aid. That’s because this specific office directly handled federal student aid.

A 1988 law clarifies the ruling

Many House Democrats perceived this Supreme Court ruling as a loophole that would let universities and colleges sidestep civil rights laws by applying them only to the specific programs that received federal funds.

In 1984, a group of Democrats unsuccessfully tried to pass legislation that would have extended civil rights protections across all programs within colleges and universities that receive federal aid for any program. A different version of this bill passed Congress with bipartisan support in 1988, on the brink of the presidential elections.

President Ronald Reagan vetoed the bill. Reagan stated in his explanation to the Senate that this bill “would vastly and unjustifiably expand the power of the Federal Government over the decisions and affairs of private organizations.”

However, many Republicans seeking reelection in Congress feared that rejecting the bill could alienate women and people of color in the upcoming election.

Within a week, Congress voted to override the veto and enacted the Civil Rights Restoration Act in 1988. This law clarified that any college accepting federal funds must comply with civil rights laws in all of its programs. This law also allowed the government to withhold federal research funding from colleges based on civil rights violations.

Enforcing civil rights laws today

The Trump administration is testing just how much the federal government can exert power over colleges and universities that receive federal funding. Some Trump administration supporters say they see this strategy as overdue enforcement against discrimination.

On the other hand, the Association of American Universities, an organization made up of American research universities, is among the opposition arguing that the administration is trying to weaponize civil rights laws to control how colleges and universities are run.

Antisemitic incidents are on the rise in the U.S., including on college campuses. But some observers have noted that the issue is nuanced, and that the administration is likely exploiting a controversial issue to achieve ideological goals.

Federal courts’ interpretations in the Harvard and UCLA lawsuits will further shape how civil rights protections are enforced at colleges and universities. Specifically, these cases will help determine whether the mere allegations of civil rights violations against a university can justify a sweeping freeze of federal research funding.

Ryan Creps does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.