In late October 2017, the Russian military deployed an advanced version of its new Kalibr cruise missile system to the border with China.
In a series of events, the US retaliated by moving an advanced cruise missile platform that it had previously deployed to Alaska, and deploying a new, more advanced missile that had previously been deployed to the United Kingdom.
Russia responded to this by deploying its own advanced cruise missiles, and it was the first time that the two countries have had direct conflict since the end of the Cold War.
This is the first installment of a series exploring how the world has come to this moment.
The first installment will focus on the US and Russia, and the two are engaged in a series, in this series, of high-level conflicts that have been taking place in recent years, including the Crimean War, the conflict in the Middle East, and now, the conflicts taking place between Russia and the US.
This article originally appeared on The Conversation.