Iran War Strains Transatlantic Alliance: Can It Endure?

The military conflict between the United States, Israel, and Iran has created a severe rift in the transatlantic alliance, leading analysts to warn that NATO is closer to a break than at any other point in its history.

The military confrontation began on February 28, 2026, with the United States and Israel launching strikes against Iranian economic and nuclear infrastructure. While the operation was led by Washington, NATO allies largely declined to participate in the war, a decision that has deepened fractures within the alliance.

On April 10, 2026, Donald Trump announced a two-week ceasefire following an agreement by Iran to reopen the Strait of Hormuz. However, the temporary cessation of hostilities has not resolved the political tension between the United States and its European partners.

A Transatlantic Stress Test

The refusal of NATO allies to join the war in Iran has been met with public condemnation from the U.S. Administration. Donald Trump described the lack of support from allies as a stain on the alliance “that will never disappear”.

Chancellor Friedrich Merz of Germany characterized the conflict as a trans-Atlantic stress test, highlighting the strategic divergence between European governments and Washington’s unilateral approach to decision-making.

There will be no return to business as usual in NATO, during neither this US administration nor the next one. We are closer to a break than we have ever been.

Jim Townsend, adjunct senior fellow at the Center for a New American Security

Reports indicate that European allies avoided the conflict for several reasons, including concerns that Iran would target them if they attempted to reopen the Strait of Hormuz.

Patterns of Erosion

Analysts suggest the crisis in Iran is not an isolated event but part of a broader pattern eroding the political foundations of NATO. Under the current U.S. Administration, Washington has engaged in several actions that have strained relations with its allies, including:

• Publicly wavering on mutual defense obligations under Article 5.
• Siding with Moscow in key United Nations General Assembly votes regarding Ukraine.
• Engaging in ill-prepared bilateral dealings with Russia.
• Issuing threats to annex Greenland, a territory of NATO member Denmark, as well as threats to annex Canada.

Monika Sus, a professor at the Institute of Political Studies of the Polish Academy of Sciences, noted that these developments are a pattern rather than one-off aberrations, occurring within the first year of the current presidency.

Strategic Divergence and Trust

The conflict has exposed a widening gap between the strategic interests of Europe and the unilateral policies of the United States. European governments have expressed concerns over their dependence on NATO and the extent to which they should align with U.S.-led policies.

Tensions were further intensified by reports that Washington engaged in back-channel deals during the push for regime change in Tehran. These arrangements suggested a willingness by the U.S. To sacrifice the political and energy security of Europe in exchange for bilateral arrangements with rivals, such as Russia, or for commercial gains.

The survival of the alliance may now depend on the ability of European nations to take a leading role in their own security. Some experts argue that the alliance can endure only if Europeans utilize NATO’s institutional framework to develop their own credible defense capabilities, moving toward a relationship based on narrower shared interests and more predictable communication.