Chinese President Xi Jinping speaks during an event to commemorate the 40th anniversary of the “Message to Compatriots in Taiwan” at the Great Hall of the People in Beijing, China January 2, 2019. Photo: REUTERS/Mark Schiefelbein/Pool.

Russian forces in eastern Ukraine are fortifying defenses and it will be hard for Kyiv’s troops to repeat the rapid success of their recent lightning counter offensive, a senior regional Ukrainian official warned on Thursday.

The sobering assessment was issued as Russian President Vladimir Putin told Xi Jinping, his Chinese counterpart, in a rare face-to-face meeting, that he understood that Xi had questions and concerns about the situation in Ukraine, but he welcomed China’s “balanced position”.

Thousands of miles to the west, Ursula von der Leyen, the president of the European Commission, was holding talks in Kyiv with President Volodymyr Zelenskiy about helping Ukraine move closer to joining the European Union.

Putin’s meeting with Xi, in Uzbekistan, was their first since they signed a “no limits” friendship agreement between their two countries, three weeks before Russia invaded Ukraine on Feb. 24. China has since trod a careful line, criticising Western sanctions on Russia but stopping short of endorsing or assisting Moscow’s campaign.

White House spokesman John Kirby said China should reject Russia’s invasion: “The whole world should be lined up against what Mr Putin is doing,” Kirby told CNN. “This is not the time for any kind of business as usual with Mr Putin.”

The Russian leader has yet to publicly comment on a severe setback suffered by his forces this month in eastern Ukraine. The stunning reversal occurred in the northeastern region of Kharkiv after Ukrainian troops made a rapid armoured thrust, forcing a rushed and chaotic Russian withdrawal which left dozens of tanks and other armoured vehicles abandoned in haste.

Kyiv says it recaptured more than 8,000 sq km (3000 sq miles), nearly equivalent to the size of the island of Cyprus. The speed of the advance has lifted Ukrainian morale, pleased Western backers who have provided arms, intelligence and training, and raised hopes of further significant gains before the winter sets in.

But Serhiy Gaidai, governor of Ukraine‘s eastern Luhansk region, warned that it would be a tough fight to wrest control of his region back from Russia, which recognises it as an independent state controlled by separatists.

“Here the Russians are digging in at Svatove and Troitske,” Gaidai told Ukrainian TV, referring to two settlements in Luhansk.

“Heavy fighting continues in many directions, including in (the) Luhansk region. The Kharkiv ‘instant scenario’ will not be repeated. We will have to fight hard for our region. The Russians are preparing for defence.”

Oleksiy Danilov, secretary of Ukraine‘s national security and defense council, said in an online post: “We should avoid euphoria. There is still a lot of work to be done to liberate our lands, and Russia has a large number of weapons.”

There was no let-up either in Russia’s daily missiles strikes on Ukraine, a day after it fired cruise missiles at a reservoir dam near Kryvyi Rih, President’s Zelenskiy’s hometown.

Authorities in the city of Kharkiv said Russian shells had hit a high-pressure gas pipeline, while a rescue operation was underway in the city of Bakhmut with four people suspected to be trapped under rubble after a strike, Pavlo Kyrylenko, the Donetsk regional governor, said.

Russian forces had launched attacks on several settlements on the Kharkiv frontline in the past 24 hours, the General Staff of Ukraine‘s Armed Forces said on Thursday.

But Britain’s defense ministry said in an update that Ukraine‘s forces were continuing to consolidate their control of newly liberated land in the region.

The United States, which has provided billions in aid to Ukraine, is expected to deliver a new security assistance package soon, White House spokesman John Kirby told MSNBC in an interview on Thursday.

Russian Foreign Ministry spokeswoman Maria Zakharova warned Washington to tread carefully, saying any decision to supply Kyiv with longer-range missiles for US-made HIMARS systems would cross a “red line” and make the United States “a direct party to the conflict”.

WAR CRIMES INVESTIGATION

On Wednesday, the first teams of war crimes prosecutors, both Ukrainian and international, gained early access to begin investigating the vast swathes of recently liberated territory.

They said initial indications were that widespread atrocities appear to have taken place.

Nigel Povoas, a British lawyer who went to the newly recaptured territory as part of an international team helping Ukraine with war crimes investigations, said the long Russian occupation of such a large area meant atrocities there were likely to have reached “an unprecedented level of horror”.

“Widespread civilian torture and executions appear to have occurred at make-shift detention centres around the region, for example, in Balakliia and Izium,” he said. The evidence so far was “following a similarly dreadful pattern” to that in cities occupied early in the war by Russian troops near Kyiv.

Russia denies that its forces commit war crimes, casting allegations as fabrications designed to besmirch the reputation of its armed forces.