How the Ukraine war could go nuclear

Not since the Cold War has the specter of nuclear war hung so heavily over a president’s crisis diplomacy.

As President Joe Biden meets with fellow NATO leaders, calls for a ceasefire in Ukraine are growing more urgent than ever — to alleviate the widespread human suffering but also to dial back what veterans of nuclear planning consider an alarming potential for it to spiral into a clash of atomic superpowers.

The nuclear brinkmanship from Russian President Vladimir Putin in recent weeks is unprecedented: He ordered a snap nuclear war game before the invasion and days later put his nuclear forces on high alert. And the Kremlin has repeatedly signaled it could resort to nuclear weapons — an option explicitly reserved in Russian military doctrine — if it determines the West’s intervention in the conflict goes too far.

Again on Tuesday, in an interview with CNN, Putin’s chief spokesperson refused to rule out the use of nuclear arms in the conflict.

So far, Biden has sought to dial down the tensions. The Pentagon has not changed the alert status of U.S. nuclear forces and military leaders have publicly said they have not detected Russian actions suggesting they are preparing to use nuclear weapons. The Pentagon also took the unusual step early in the conflict of putting off a regularly scheduled test of an intercontinental ballistic missile to avoid fueling nuclear tensions.