As Ukrainian and Western officials responded to discoveries of mass graves and streets littered with the bodies of dead civilians after Russia’s retreat from suburbs around Kyiv, calls for war crimes investigations and tougher sanctions against Moscow grew louder Monday.

Even as Kyiv, the Ukrainian capital, enjoys a reprieve, European nations, including the United Kingdom, Germany, France, and Spain, have vowed to punish Russia for alleged atrocities in a war that is now in its 40th day. New strikes were reported overnight as Russia’s military focus appeared to shift to the south and east, including on the historic Black Sea port of Odesa and the city of Mykolaiv, both in the south. There was no information on deaths or injuries.

Ukrainian President Volodymyr Zelensky warned in an overnight video address that the most brutal images from newly liberated areas such as Bucha, northwest of Kyiv, were yet to come. Since invading Russian troops left last week, the Ukrainian government said it had counted 400 civilian deaths in Kyiv suburbs, including the devastated town of Irpin.

The scenes in Bucha, where photos and videos show mass graves and dead men and women lying face down on residential streets, have been described by Zelensky as evidence of Russian “genocide” against Ukrainians. He promised to establish a special judicial mechanism to investigate alleged war crimes, with the participation of international prosecutors and judges.

The gruesome scenes have sparked international outrage and calls for Russia to be held accountable.

The gruesome images were described as “unbearable” by French President Emmanuel Macron on Monday. Macron, who has stated his support for more sanctions, stated that Russia has committed “clear” war crimes.

And a top government official in Germany, a major importer of Russian gas and one of the most adamant opponents of a ban, hinted on Sunday that the country might change its mind and support one. Defense Minister Christine Lambrecht stated, “There has to be a response.” “Such atrocities must not go unpunished.”

Russia supplies more than half of Germany’s gas. Russia supplies 40 percent of Europe’s gas and 25 percent of its oil.

Dmitry Peskov, a spokesman for the Kremlin, said the images coming out of Bucha were fakes during a daily news briefing on Monday. Peskov stated, “We categorically deny any allegations.”

Russia has denied targeting civilians in Ukraine on numerous occasions. The United States, the United Nations, and humanitarian organizations have all stated the opposite.

Despite never being able to enter central Kyiv, Russian President Vladimir Putin’s government announced that the “first phase” of Russia’s war against Ukraine had been completed and that its forces were moving east to the industrial region of Donbas and other areas where pro-Russia separatist movements exist.

According to regional governor Viacheslav Chaus, Russian troops appeared to have left several towns around the northeastern city of Chernihiv by Monday. Chaus, who estimates that about 70% of the city has been destroyed, warned residents not to become complacent. He advised patience as Ukrainian troops cleared mines in a message posted to the Telegram app.

For weeks, major aid routes into the city have been blocked, but RBK Ukraina, a Ukrainian news outlet, reported a positive development: On Monday morning, the 92-mile car route between Kyiv and Chernihiv was partially reopened.

The local prosecutor’s office in Kharkiv, Ukraine’s second-largest city, said Monday that shelling of residential buildings on Sunday killed seven people and injured 34 others.

Even as war rages in the south and east, the shifting terrain of war has left western Ukraine in relative peace as local recovery efforts begin. Russian fighters were in a “consolidate and reorganize” phase, according to the British Ministry of Defense, as they planned more offensives in Donbas. Wagner, a Russian paramilitary company, was said to be staging in the area, according to the ministry.

At the same time, the Ukrainian military said in a Monday report that Russians were preparing a “hidden mobilization” to regroup as they withdrew from parts of Ukraine.

Since Russia launched the war on February 24, at least 1,417 civilians have been killed, according to the United Nations. Approximately a quarter of Ukraine’s 44 million people have been displaced, with over 4 million fleeing the country.