President Trump’s deference to Russia, his unprecedented rebuke of Volodymyr Zelensky and his no-holds-barred approach in prodding European partners to spend more on their military budgets are having an unintended impact among America’s longtime allies: a possible nuclear free-for-all.

In recent days, emergency meetings have been convened in foreign capitals, and alarming public statements have been delivered by Poland, Germany and South Korea about their consideration of acquiring nuclear weapons. It’s a remarkable turn of events that portends a new nuclear landscape.

America’s European and Asian allies haven’t contemplated their nuclear futures this earnestly — and openly — since the dawn of the atomic age. For decades, they have relied on Washington’s policy of extended deterrence, which, by dint of treaties, promises more than 30 allies safety under America’s nuclear umbrella in exchange for forgoing the development of their own arsenals. The nations don’t need nuclear weapons to deter adversaries from a nuclear attack, according to the policy, because the United States guarantees to strike back on its allies’ behalf.