KHARKIV, Ukraine — Ukrainian President Volodymyr Zelensky on Sunday said Ukraine and Russia would conduct the first diplomatic talks since the Kremlin-launched invasion, with delegations from both countries meeting at the Ukrainian border with Belarus. The two countries would meet near the Pripyat River “without preconditions,” Zelensky’s office said in a Telegram message.

But tensions continued to escalate, with Russian President Vladimir Putin stating Sunday that he had put his nuclear deterrence forces into high alert, attributing the move to “aggressive statements” from the West against Russia. The White House called the order an example of “manufacturing threats that don’t exist.”

The European Union, meanwhile, announced it will shut down airspace to Russian planes and finance weapons purchases to Ukraine as several nations, including the United States, vow to block the Kremlin’s access to its sizable foreign currency reserves in the West and to cut off some Russian banks from the SWIFT financial messaging system. Those sanctions, The Washington Post reports, followed an emotional call from Zelensky, in which he pleaded for help.

Earlier Sunday, Russian forces pushed into Kharkiv, sparking a battle for control in Ukraine’s second-largest city. By afternoon local time, the city was quieter, with the sounds of bombardment fading from downtown and Kharkiv’s governor announcing that the city remained under government control.

Here’s what to know

  • The Pentagon is criticizing Putin’s decision to put his nuclear forces on high alert as “unnecessary” and “escalatory,” but remains confident that the United States and NATO will be able to defend themselves, according to a senior defense official.
  • Delivery companies UPS and FedEx have suspended shipments into Russia, as well as shipping services to and from Ukraine amid the ongoing conflict.
  • British oil giant BP said it will “exit” its 20 percent stake in Russian oil giant Rosneft after Moscow’s invasion of Ukraine, in one of the biggest signs yet of the Western business world cutting ties over the Kremlin’s actions.
  • Over four days of fighting, the United Nations’ refugee agency said Sunday that 368,000 people have fled Ukraine.