# US-Denmark-Greenland Arctic security cooperation > Live situation record from CLSTR: https://clstr.news/situations/us-denmark-greenland-arctic-security-cooperation > Updated: 2026-10-06T14:22:20.000Z. Sources: 830. Developments: 2. The United States, Denmark, and Greenland have entered into a trilateral security agreement to expand American military presence in the Arctic. This accord facilitates the modernization of the Pituffik Space Base and the creation of new defense areas in Narsarsuaq and Mestersvig. Under the agreement, the U.S. may deploy a ‘Golden Dome’ defense system against ballistic missile threats and is granted broad operational access to Greenlandic airspace and territorial waters. Additionally, non-NATO countries are barred from establishing military bases or making sensitive investments in Greenland without U.S. approval. Following this agreement, U.S. Special Operations Command North established Operation Apex Indigo to consolidate special operations activities in the region. This framework, developed alongside Danish and Greenlandic partners, focuses on cold-weather survival and remote terrain movement to improve interoperability with NATO Arctic allies. The initiative aims to strengthen collective deterrence through recurring multinational training exercises. ## Timeline ### 2026-10-06: U.S. Special Operations Command expands Greenland training U.S. Special Operations Command North has launched Operation Apex Indigo to unify and expand special operations training and Arctic deterrence in Greenland alongside Danish and NATO partners. 2 sources. https://clstr.news/cluster/us-special-operations-command-expands-greenland-training ### 2026-09-20: Greenland security deal expands US military presence in the Arctic The US, Denmark, and Greenland have signed a security deal to expand US military presence in the Arctic, including new defense areas and a 'Golden Dome' missile defense system. 828 sources. https://clstr.news/cluster/mayor-mamdani-and-president-trump-to-meet-at-gracie-mansion --- Cite as: US-Denmark-Greenland Arctic security cooperation. CLSTR, https://clstr.news/situations/us-denmark-greenland-arctic-security-cooperation