(Bloomberg) -- Traffic is returning and sidewalk cafes are filling up in Kyiv, but two of the city’s most world-famous residents say the lethal danger of war means the city still isn’t safe.

Vitali Klitschko, the former world heavyweight boxing champion who became the capital’s mayor in 2014, and his younger brother Wladimir said the 1.5 million people who have come back to the city are doing so at their own risk. 

“Everybody asks me, ‘can we come back now?’” Vitali said in an interview on Tuesday in Davos, Switzerland. “I tell them, our priority is safety, and we can’t give guarantee safety for every citizen because every second, every minute a Russian rocket can land in an apartment building. That’s why we say to everyone if you decide to come back it is at your own risk.”

While shops and restaurants are reopening and foreign diplomats returning to their embassies after evacuating early in the war, about 1 million people displaced from Kyiv’s pre-war population of 3.5 million have yet to return.

Public transportation remains spotty, a curfew is still in place and some neighborhoods are pocked with land mines planted by Russian forces. Lines of cars at gas stations illustrate fuel shortages, while companies are struggling to restart business without employees who’ve fled, been drafted into the military, or suffered worse fate.

The mayor said his administration has introduced tax breaks to help get the economy back on its feet but said returning to normal will take time.

“Life is coming slowly back,” he said. “We see many more people in the streets. We can’t forbid them to come. Everyone decides by themselves.”

Wladimir Klitschko, a former world heavyweight champion himself who, like Vitali, joined the Kyiv Territorial Defense Brigade when war broke out, urged the world to stay committed to helping Ukraine in its struggle against Russia’s invasion.

“We need to solve this problem and stop this war now, together,” he said. “If not, the consequences are going to be severe for the world. Hunger is one of the issues.”

Both men urged global leaders to isolate President Vladimir Putin’s government so that it can’t finance the war. That includes banning the purchase of oil and gas from Russia, which must also be excluded from the next Olympic Games and other global events, Wladimir said.

“It’s going to hurt Russia,” he said. “We have to show that the world is not OK with that.”

The brothers voiced gratitude for the help Ukraine and its citizens were receiving on the military and humanitarian front. But they said more must be done.

“It’s never enough,” Wladimir said. “As long as this war still goes on, it’s never enough.”

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