What is NATO? And why is it still around? This video was part of our 2020 US election series. Watch more at http://vox.com/ElectionVideos For 150 years, the US avoided formal alliances. It occasionally went to war -- fighting the War of 1812, the Spanish-American War, and World War I -- but did so without entangling itself in promises to other countries. Then, after World War II, it abruptly changed course, and began to build a network of alliances unlike anything that had come before. Over the next few decades, the US used those alliances to keep countries around the world close, and to fight Soviet expansion, by making a promise that it would go to war if any of its allies were ever attacked. After the Soviet Union fell, the initial purpose of those alliances was gone, but the US recommitted to them, signaling again and again that the central promise of those relationships was still in effect. It kept doing so for the next 25 years. Then the US elected a leader who took America’s global relationships in a new direction. President Trump was skeptical that America’s network of alliances was still beneficial to the US. He began to distance the US from those alliances, raising doubts about whether America would actually follow through on the promise at the core of them if provoked. Some allies moved closer to Russia or China, both of whom had attempted to undermine America’s alliances. Today, the future of those alliances is on the ballot in the US. One of the major presidential candidates in the 2020 election wants to return the US to its former status with its allies; the other finds its decades-old alliances costly and cumbersome. The world is waiting to see which vision Americans prefer. This was the sixth in our series of 2020 election explainers, all based on viewer suggestions. Watch the others, which cover the stakes of the election on: 1) Climate change: https://www.youtube.com/watch?v=QfAXbGInwno 2) Voting rights: https://www.youtube.com/watch?v=al3qY8ZMHEc 3) Reproductive health: https://www.youtube.com/watch?v=Bzuk13Ftxgo 4) Public schools: https://www.youtube.com/watch?v=lFJ37ri-Saw 5) Police reform: https://www.youtube.com/watch?v=SHePglP28CM 6) America’s role in the world: https://www.youtube.com/watch?v=S5LrQv496Iw 7) Transportation: https://www.youtube.com/watch?v=-ZDZtBRTyeI 8) LGBTQ rights: https://www.youtube.com/watch?v=xRnpUptf7E0 9) The eviction crisis: https://www.youtube.com/watch?v=F07yTI0J3Qk Sources and further reading: Alex Ward: https://www.vox.com/2020/8/18/21334630/joe-biden-foreign-policy-explainer Mira Rapp-Hooper, Shields of the Republic: https://www.amazon.com/Shields-Republic-Triumph-Americas-Alliances/dp/0674982959 Mark Webber and James Sperling: https://www.cambridge.org/core/services/aop-cambridge-core/content/view/CECD6A4DA95D3C177531E8C10A6E562B/S0260210519000123a.pdf/trumps_foreign_policy_and_nato_exit_and_voice.pdf Joyce Kaufman: https://www.chathamhouse.org/sites/default/files/publications/ia/INTA93_2_01_Kaufman.pdf Jennifer Lind: https://americas.chathamhouse.org/article/the-future-of-americas-ailing-alliances/ Klaus Larres: https://archive.transatlanticrelations.org/wp-content/uploads/2017/05/Larres-Donald-Trump-and-America%E2%80%99s-Grand-Strategy-U.S.-foreign-policy-toward-Europe-Russia-and-China-Global-Policy-May-2017.pdf Fabrice Pothier and Alexander Vershbow: https://www.atlanticcouncil.org/wp-content/uploads/2017/05/NATO_and_Trump_web_0623.pdf Elena Atanassova-Cornelis: https://www.tandfonline.com/doi/full/10.1080/03932729.2019.1665272 Shin Kawashima, Matake Kamiya, James L. Schoff: https://carnegieendowment.org/2019/10/10/managing-risks-and-opportunities-for-u.s.-japan-alliance-through-coordinated-china-policy-pub-80026 Subscribe to our channel! http://goo.gl/0bsAjO Vox.com is a news website that helps you cut through the noise and understand what's really driving the events in the headlines. Check out http://www.vox.com/. Watch our full video catalog: http://goo.gl/IZONyE Follow Vox on Facebook: http://goo.gl/U2g06o Or Twitter: http://goo.gl/XFrZ5H