By Fen Osler Hampson

April 13, 2026

There is a bucket of trouble in Donald Trump’s naval blockade of the Strait of Hormuz, which began today. It will inevitably bring renewed pressure on NATO allies to provide tangible support for Trump’s war, which they refuse to do.

This time, his ask could be to send ships to enforce the blockade, particularly if there is a prolonged standoff. For what it’s worth, Trump already said on Fox News on Sunday that he thinks “other nations will be supporting us on this.”

Britain’s Keir Starmer said on Sunday that the U.K. won’t participate in the blockade, though naval escorts and mine-clearing assistance could be offered after hostilities end. Trump, who seems to enjoy berating the British Prime Minister, has compared Starmer to Neville Chamberlain. He has also compared himself to Jesus Christ, so that’s also for what it’s worth.

But Trump seems even more unhappy with the rest of NATO’s members, who refuse to support his war, especially France, Spain and Italy, which have restricted the use of their airspace and facilities to U.S. operations related to the Iranian operation. European opposition to the blockade could be the last straw, prompting a repositioning or withdrawal of U.S. troops from Europe, as Trump has already threatened.

Twenty-one hours of talks in Islamabad this past weekend, aimed at ending the war and led by Vice President JD Vance, with Steve Witkoff and Jared Kushner in attendance, failed to produce a deal. Vance said the Iranians “chose not to accept our terms.” Tehran complained about American “overreach” and “failure to gain the trust” of the Iranian delegation.

Within hours, Donald Trump announced on Truth Social that the United States Navy would begin “the process of BLOCKADING any and all Ships trying to enter, or leave, the Strait of Hormuz.” A fragile two-week ceasefire, struck just five days ago and set to expire on April 21, hangs by a thread as Trump threatens further military attacks. What comes now is far more dangerous than most Western capitals are prepared to admit.

The risks of miscalculation, whether through a collision in a dangerous game of cat-and-mouse on the high seas or a warning shot fired across the bow of a vessel trying to run the blockade, could easily escalate into open warfare and perhaps even worse.

A naval blockade is neither a sanction nor a strongly worded communiqué. It is an act of war intended to assert US military control over one of the most consequential choke points on earth. One-fifth of the world’s oil transits the Strait of Hormuz. The United States has now claimed, through a presidential social media post, the right to interdict any vessel that pays what Trump called “EXTORTION” tolls to Iran.

This brings us to the actions of a former U.S. president, John F. Kennedy. During the Cuban Missile Crisis of October 1962, Kennedy imposed a naval “quarantine” — a diplomatic euphemism for a blockade — on Cuba to stop Russian ships carrying nuclear-armed missiles from delivering their deadly cargo. The world stood on the brink of nuclear war for thirteen days, waiting to see who would blink first. In the end, it was Premier Nikita Khrushchev who blinked and ordered Russian ships to turn around.

The parallels with today’s crisis in the Persian Gulf are not reassuring. If Russia or China — both of which have strategic and economic interests in trading with Iran to balance against their interest in keeping Trump’s presidency undisturbed as an asset to their geopolitical designs — decide to test the American blockade by escorting merchant vessels or tankers with their own naval forces, an incident at sea is easy to imagine.

The risks of miscalculation, whether through a collision in a dangerous game of cat-and-mouse on the high seas or a warning shot fired across the bow of a vessel trying to run the blockade, could easily escalate into open warfare and perhaps even worse.

For Canada, the timing cannot be decoupled from our principal economic file with Washington — the looming CUSMA review. USTR Jamieson Greer confirmed on April 7 that CUSMA issues are unlikely to be resolved by the July 1 review deadline, with talks potentially extending into 2027, well past the November congressional elections.

Greer may be reflecting an assumption on the part of the administration that when the Gulf crisis ends and its impact on energy markets has spawned a new status quo, Canada’s current energy leverage in a world of oil and gas supply shortages and price shocks will weaken.

In other words, he may be betting that if the Gulf crisis stabilizes on American terms, Canada will have lost its best card before a single CUSMA chapter is renegotiated.

Policy Contributing Writer Fen Osler Hampson, FRSC, is the Chancellor’s Professor and Professor of International Affairs at Carleton University, and president of the World Refugee & Migration Council. He is co-chair of the Expert Group on Canada-US Relations.