US armed forces act on Canadian territory or in waters Canada claims, without Canada's consent
The test Between 26 Oct 2026 and 30 Sep 2027, US armed forces take a military action on Canadian territory or in waters Canada claims, without Canada's consent (Strature F-0178).
Not under way · Confidence: medium · Reviewed 26 Oct 2026 · Scores from 1 to 10
This page answers: What could happen, how it is scored, and who is exposed?
Using this page
- Read the two scores: Likelihood and Impact are kept apart.
- Check what is happening, each fact with its source.
- Use the calendar for the dates to watch.
Follow this riskSign in to follow; one weekly email if you ask for it.
Impact is the average of the four parts, rounded, plus one point when Canada is directly hit on two or more channels, up to 10.
Two separate scales from 1 to 10. Strature never multiplies or merges them.
What changed
Dated, newest first
- US President called the EU's associate-member idea for Canada a hostile act [4]
- Bank of Canada 2025 annual average: C$1.3978 per US$ [12]
- Strature brief C-006 asks whether the United States tests the Northwest Passage without Canada's consent [3]
- Strature forecast F-0178: 2% (1 Oct 2026), resolves 30 Sep 2027 [2]
- 35 full Northwest Passage transits in 2025, 6 commercial; SOR/2025-275 replaced NORDREG 31 Mar 2026 [7]
- Carney called US military action an extreme tail risk and said Canada prepared for it; McGuinty called risk-scenario analysis normal [1]
Why it matters
The Prime Minister told the New York Times in September 2026 that Canada has prepared for US military action against it, an 'extreme tail risk'. Strature registers 2% that US forces act on Canadian territory or in waters Canada claims without consent by 30 Sep 2027 (Strature forecast F-0178, 1 Oct 2026). The live legal fault line is the Northwest Passage: Washington calls it an international strait, Ottawa calls it internal waters.
Why Likelihood 2 Pushes: Canada's government prepared for it; the unresolved Northwest Passage dispute; strained relations. Brakes: the 1988 consent practice; NORAD; the US President called an invasion highly unlikely (May 2025).
Why Impact 6 Threshold case a single limited act, not war.
The other facts on file (5)
- US treats the Northwest Passage as an international strait; Canada drew Arctic baselines in 1985 and claims internal waters [5] (28 Jul 2025)
- 1988 Agreement on Arctic Cooperation: US icebreaker navigation in waters Canada claims as internal undertaken with Canada's consent; legal positions unaffected (Articles 3 and 4) [6] (11 Jan 1988)
- Canada a NORAD partner; in talks on Golden Dome, May 2025 [8] (21 May 2025)
- US share of Canada's merchandise exports 71.7% in 2025 [9] (19 Feb 2026)
- Canadian merchandise exports to the US fell 5.3% in 2025 to C$564.6bn [11] (8 Jun 2026)
Where it sits
How it spreads
Between 26 Oct 2026 and 30 Sep 2027, US armed forces take a military action on Canadian territory or in waters Canada claims, without Canada's consent (Strature F-0178).
Not under wayChannels 4 on the card
- Sovereignty and defenceBreaks the 1988 consent practice [6] and tests NORAD [8].
- TradeSits on top of the trade dispute with Canada's largest market, the destination of 71.7% of its merchandise exports in 2025 [9].
- AlliancesOttawa turns harder to Europe.
- Arctic shippingA contested legal status on a route few ships use.
Sectors 1
- Ports and logistics
Countries 2
- Canada primary
- United States
Who is exposed
- Countries
- Canada, United States
- Sectors
- Defence, Ports and logistics, Energy and pipelines, Mining and metals
- Straits
- Northwest passage
Three scenarios and their signposts
- S1
Managed disagreement
Both sides keep the 1988 consent practice; US ships ask and Canada consents.
- S2
A test of the strait
A US Navy or Coast Guard vessel transits the Passage asserting transit rights without consent.
- S3
Wider coercion
Pressure moves from trade into defence, such as a NORAD row or basing demands.
| Path | Signpost |
|---|---|
| S1 | US icebreaker voyages notified to Ottawa |
| S2 | A US statement naming the Passage an international strait during a voyage |
| S3 | A US official statement linking defence access to trade terms |
No probability is given for the three paths.
Forecasts
Strature forecast linked to this risk
Strature forecast F-0178: 2% (1 Oct 2026) · resolves by 30 Sep 2027
Where the card uses it F-0178 resolves. Strature forecast F-0178: 2% (1 Oct 2026)
A forecast is a probability on a dated question. The Likelihood score above is a separate judgement and is never turned into a percentage.
The forecast register lists every forecast and how it is scored.
Dates to watch
The dates to watch
A dot is a day, a bar a month or a year; a hollow mark is tentative. The line marks today.
- 30 Sep 2027 F-0178 resolves. Strature forecast F-0178: 2% (1 Oct 2026) [2] Declared · Strature date
- 14 Oct 2027 F-0178 scored. Strature forecast F-0178: 2% (1 Oct 2026) [2] Declared · Strature date
- 2028 First Canadian F-35s arrive in Canada [1] Tentative · Outside event
Sign in, with alerts on, for an email 7 days and 1 day before.
The other side
The risk pushes Canada to build its own Arctic capacity, from under-ice gliders to the Churchill build and a sovereign satellite network, work that also serves shipping and northern communities. A clear test could also bring the two sides to settle Passage rules by agreement (Strature's view).
Connected in Strature
- Canada: Access by List
- Is the Northwest Passage becoming a shipping lane?
- US tariffs and Canada
- Canada
- United States
- The US tariff wall around Canada and Mexico stays up or grows Driven by: The trade dispute is the backdrop to Ottawa's preparations (Strature's reading).
- The Canada-EU summit delivers none of its drafted deals by 31 Dec 2026 Shares a channel: Both turn on Canada's move towards Europe (Strature's view).
Sources
12 sources, numbered as the text cites them
- Defence minister says it's normal to analyze risk scenarios amid Carney's US military comments. BNN Bloomberg (CTVNews.ca, The Canadian Press) · 23 Sep 2026 · News · confidence medium · retrieved 25 Oct 2026
- Forecast register and key question KQ-18. Strature · 2026-10 · Think tank · confidence high · retrieved 25 Oct 2026
- C-006: Canada: Access by List (Edition 1.6). Strature · 5 Oct 2026 · Think tank · confidence medium · retrieved 25 Oct 2026
- Canada-EU summit seeks deepened alliance as US ties fray (AFP). France 24 · 26 Oct 2026 · News · confidence medium · retrieved 26 Oct 2026
- Explainer: The Northwest Passage's shipping potential, legal status, and what's at stake. Belfer Center, Harvard Kennedy School · 28 Jul 2025 · Think tank · confidence medium · retrieved 25 Oct 2026
- Agreement between the Government of Canada and the Government of the United States of America on Arctic Cooperation. Government of Canada Treaty Information · 11 Jan 1988 · Official · confidence high · retrieved 25 Oct 2026
- T-002: Is the Northwest Passage becoming a shipping lane?. Strature · 30 Sep 2026 · Think tank · confidence medium · retrieved 25 Oct 2026
- Canada in 'Golden Dome' talks with US. The Hill · 21 May 2025 · News · confidence medium · retrieved 25 Oct 2026
- Canadian international merchandise trade, December 2025. Statistics Canada · 19 Feb 2026 · Official · confidence high · retrieved 25 Oct 2026
- Prime Minister Carney to strengthen Canada's ties with European partners. Prime Minister of Canada · 12 Sep 2026 · Official · confidence high · retrieved 25 Oct 2026
- Highlights of Canada's merchandise trade performance, 2025 update. Global Affairs Canada (Office of the Chief Economist) · 8 Jun 2026 · Official · confidence high · retrieved 26 Oct 2026
- Annual Exchange Rates. Bank of Canada · undated · Official · confidence high · retrieved 26 Oct 2026
Reviewed 26 Oct 2026 · version 1 · last change: reviewed · All risks