World War III is starting.
Also, not shown in these links, largely as a result of the ongoing war in Syria and Iraq and its refugees, Turkey is suffering an unprecedented crackdown on human rights, and Europe and the US are experiencing levels of xenophobia unprecedented since the lead up to WWII, resulting in a resurgent fascist movement, which incidentally Russia blames for the most recent coup in Ukraine and used as justification for reannexing Crimea, and which got their candidate nominated as the US Republican Party's presidential candidate. And the European Union is splitting apart. Also, two nuclear powers are fighting in Jammu and Kashmir.
On top of all this, related to old Vlad's point about PGMs but not fully explained in it, war tactics have changed so much since the last war between great powers that it is inevitable that some great-power militaries have doctrines that are likely to just get their people slaughtered, as happened to the Iraqi army in the US invasions, or more evocatively the futile bayonet charges in the Russo-Japanese war and World War I. That means that nobody can predict what the outcome of a possible conflict will be, which increases the chances that both sides think they can win it.