Russian President Vladimir Putin said on Friday during a visit to China that Moscow’s offensive in Ukraine’s northeastern Kharkiv region aims to create a buffer zone but that there are no plans to capture the city.

The remarks were Putin’s first on the offensive launched May 10, which opened a new front and displaced thousands of Ukrainians within days. Earlier Friday, a massive Ukrainian drone attack on the Russia-occupied Crimean Peninsula cut off power in the city of Sevastopol, after an earlier attack damaged aircraft and fuel storage at an airbase.

In southern Russia, Russian authorities said a refinery was also set ablaze.

Moscow launched attacks in the Kharkiv region in response to Ukrainian shelling of Russia’s Belgorod region, Putin told reporters while visiting the Chinese city of Harbin.

“I have said publicly that if it continues, we will be forced to create a security zone, a sanitary zone,” he said. “That's what we are doing.” Russian troops were “advancing daily according to plan," he said and added there were no plans for now to take the city of Kharkiv.

Ukrainian troops are fighting to halt Russian advances in the Kharkiv region that began late last week. In an effort to increase troop numbers, President Volodymyr Zelenskyy signed two laws Friday, allowing prisoners to join the army and increasing fines for draft dodgers fivefold. The controversial mobilization law goes into effect on Saturday.

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Russia enlisted prisoners early on in the war, and personnel shortages compelled the new measures. The legislation allows for “parole from serving a sentence and further enlistment for military service" for a specific period for some people charged with criminal offences. It doesn't extend to those convicted of crimes against Ukraine’s national security.

Penalties will be increased to 25,500 hryvnias ($650) for citizens and 51,000 hryvnias ($1,300) for civil servants and legal entities for ignoring draft notices or failing to update the draft board of their information. Fines were previously 5100 hryvnias ($130) for citizens and 8500 hryvnias ($215) for civil servants and legal entities.

Ukrainian authorities have evacuated around 8,000 civilians from the recent flashpoint town of Vovchansk, 5 kilometers (3 miles) from the Russian border. The Russian army’s usual tactic is to reduce towns and villages to ruins with aerial strikes before troops move in.

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At least two people were killed and 19 were wounded in the Russian bombing of Kharkiv, regional chief Oleh Syniehubov said on his Telegram posting on Friday. Four of the wounded were in critical condition.

Russia's new offensive has “expanded the zone of active hostilities by almost 70 kilometers” (45 miles), in an effort to force Ukraine to spread its forces and use reserve troops, Ukraine’s military chief, Col. Gen. Oleksandr Syrskyi, said Friday.

In the Kharkiv region, Russian forces have advanced 10 kilometers (6 miles) from the border, Zelenskyy said Friday.

Separately, speaking about Ukraine’s upcoming peace conferences in Switzerland next month, Putin said it was a vain attempt to enforce terms of a peaceful settlement on Russia and stressed that Russia wasn’t invited to the meeting.

He said that Russia was ready for talks but shrugged off Zelenskyy’s peace formula as wishful thinking. Any prospective peace talks should be based on a draft deal negotiated by Russia and Ukraine during their Istanbul talks in 2022, he said.

Ukraine meanwhile carried out drone raids on Crimea in an attempt to strike back during Moscow's offensive in northeastern Ukraine, which has piled on pressure on outnumbered and outgunned Ukrainian forces awaiting delayed deliveries of crucial weapons and ammunition from Western partners.

A Ukrainian intelligence official confirmed to The Associated Press that the country's intelligence services struck Russia’s military infrastructure sites in Novorossiysk, on the Black Sea coast, and in Russian-occupied city of Sevastopol. The official was not authorized to make public comments and spoke on condition of anonymity.

The operation, carried out by Ukraine-built drones, targeted Russian Black Sea Fleet vessels, the official said.

The Russian Defense Ministry said air defenses downed 51 Ukrainian drones over Crimea, 44 over the Krasnodar region of Russia and six over the Belgorod region. Russian warplanes and patrol boats also destroyed six sea drones in the Black Sea, it said.

At least three fighter jets were destroyed in an earlier attack in Crimea a few days ago, according to satellite imagery of the airbase provided by Maxar Technologies.

Mikhail Razvozhayev, the governor of Sevastopol, which is the main base for Russia's Black Sea Fleet, said the drone attack damaged the city’s power plant. He said it could take a day to fully restore electricity and warned residents of power cuts. He also announced city schools would be closed temporarily.

In the Krasnodar region, authorities said a drone attack early Friday caused a fire at an oil refinery in Tuapse, which was later contained. There were no casualties. Ukraine has repeatedly targeted refineries and other energy facilities deep inside Russia, inflicting damage.

The Krasnodar region’s governor, Veniamin Kondratyev, said fragments of downed drones around the port of Novorossiysk caused several fires, but there were no casualties.

Belgorov Gov. Vyacheslav Gladkov said a Ukrainian drone struck a vehicle, killing a woman and her 4-year-old child. Another attack there set a fuel tank ablaze at a gas station, he said.

Recent Russian attacks have also targeted the eastern Donetsk region, as well as the Chernihiv and Sumy regions in the north and in the southern Zaporizhzhia region — apparently seeking to further stretch depleted Ukrainian resources.

Having boosted their forces in northern Ukraine, Russian forces are now pushing to advance near the village of Lyptsi, as well as the town of Vovchansk, according to Syrskyi, the Ukrainian military commander.

Syrskyi also said he inspected units that are “preparing for defense” of Sumy. On Tuesday, the head of Ukraine’s Military Intelligence, Kyrylo Budanov, reportedly said Russia's military planned to launch offensive actions in Sumy.

Russia has also been testing defenses elsewhere along the roughly 1,000-kilometer (620-mile) front line, which snakes north-to-south through eastern Ukraine. The line has barely changed over the past 18 months, in what has become a war of attrition.