The heads of three governments in the European Union — the Czech Republic, Poland and Slovenia — are traveling to Kyiv to meet with Ukrainian President Volodymyr Zelensky. The visit, at a moment when Europe is engaged in an extraordinary effort to isolate Russian President Vladimir Putin, is meant to “confirm the unequivocal support of the entire European Union for the sovereignty and independence of Ukraine,” the Czech prime minister said in a Facebook post.

The visit comes as fierce fighting rages across Ukraine. A Fox News cameraman, Pierre Zakrzewski, was killed in Ukraine, Fox News said Tuesday – the second journalist to be killed in the country in recent days. In the capital, a suspected Russian missile attack on another apartment building Tuesday killed at least four people. Kyiv’s mayor announced a curfew, citing a “difficult and dangerous moment” without specifying details. Officials were once again struggling to get humanitarian aid to the southern port city of Mariupol, which is surrounded by Russian troops. Videos captured blasts striking at least three locations in the heart of Kharkiv, Ukraine’s second-largest city, on Monday night.

A United Nations agency said more than 3 million people have fled Ukraine since Russia’s invasion nearly three weeks ago. Ukrainian officials have reported progress in opening “humanitarian corridors” to besieged cities. Officials in Sumy province said Tuesday that evacuation routes would be opened from several cities in the region, in northeastern Ukraine near the Russian border. And in Mariupol, the city council said 2,000 cars had left the city by 2 p.m. local time.

Talks between Ukraine and Russia resumed Tuesday after what Ukrainian negotiators on Monday described as a “technical pause.” Zelensky is scheduled to deliver a virtual joint address to the U.S. Congress on Wednesday.

Here’s what to know

  • While Moscow has gained control of southern cities such as Kherson and Melitopol, it is struggling to take over Mariupol, along with hubs across Ukraine such as Kharkiv, Chernihiv and Sumy. Military analysts say Ukraine’s main aim is to buy time — sapping Russian troop morale and allowing other pressures to build on Putin.
  • Multiple demonstrations have taken place over several days in the Russian-occupied cities of Kherson, Melitopol and Berdyansk, British defense intelligence officials said Tuesday. Reports suggest Moscow may seek to stage a “referendum” in Kherson, they added, in a bid to create another “breakaway republic” similar to separatist areas in Donetsk and Luhansk in eastern Ukraine, in addition to Crimea, which Russia annexed in 2014.
  • A United Nations human rights office, which has been tracking civilian casualties, confirmed the deaths of at least 636 civilians, including dozens of women and children, and said at least 1,125 others have been injured since Russia began its invasion — although the office acknowledges that the tolls are incomplete.