The world can breathe a small sigh of relief this week. The last remaining arms control treaty between the United States and Russia, called New START, will not expire on Feb. 5 after all, as recently feared.

In the nick of time, Russian President Vladimir Putin offered his new American counterpart an extension of the treaty for five years, an option stipulated in its text. Joe Biden agreed — after giving Putin the requisite talking to about Russia’s massive cyberattack on the United States, its jailing of the activist Alexey Navalny and other recent outrages.

In the short term, a new nuclear arms race between the two biggies has thus been avoided. Sort of. But not really — and there’s the rub. A wider glance at the world’s nuclear landscape reveals that the danger of cataclysm, by design or accident, keeps growing.