Ukrainian President Volodymyr Zelenskiy says his country's assault on Russia's Kursk region shows that Kremlin threats of retaliation are a bluff, and he urged Kyiv's allies to loosen curbs on using foreign-supplied weapons.
Zelenskiy said Ukrainian forces now controlled more than 1250 square kilometres and 92 settlements in Kursk region, while Russia said Ukraine had struck a third bridge in the region, complicating Russian efforts to repel the Ukrainian attack.
Ukraine launched its surprise strike on the Russian region on August 6, the biggest invasion of Russia since World War II, in an operation that Kyiv says is aimed at carving out a buffer zone and wearing down Russia's war machine.
Speaking to a gathering of Ukrainian diplomats, Zelenskiy singled out allies who have supplied long-range weapons but told Kyiv they cannot use them deep inside Russia for fear of crossing "red lines" set out by Russian President Vladimir Putin.
"We are witnessing a significant ideological shift - the naive, illusory concept of so-called red lines regarding Russia, which dominated the assessment of the war by some partners, has crumbled apart these days," he said.
He said Ukraine, because of the restrictions imposed by allies, could not use the weapons at its disposal to hit some Russian military targets.
Zelenskiy urged allies to be bolder in their decisions about how to help Kyiv in the war.
"The world sees that everything in this war depends only on courage - our courage, the courage of our partners. On brave decisions for Ukraine, on courage in supporting Ukraine," he said.
But Ukrainian forces are on the defensive elsewhere and face a battle to protect the strategic eastern city of Pokrovsk, where Russia has steadily advanced in recent weeks in heavy fighting more than two years since Russia's full-scale invasion.
"We are achieving our goals," Ukrainian President Volodymyr Zelenskiy wrote of the two-week-old incursion into Kursk on the Telegram messaging app on Monday, adding that more Russian soldiers had been taken prisoner.
Russia said a third bridge had been struck and damaged on the Seym River that winds through the Kursk region bordering northeastern Ukraine.
Ukraine has not yet commented on the strike but the country's air force chief has previously said his forces have destroyed two bridges to weaken enemy logistics.
Military analysts said the bridges were part of critical supply lines for Russian troops defending the area.
Reuters could not independently confirm the damage to the bridges or the battlefield situation in Kursk.
More than 121,000 people have been relocated from nine border districts in the Kursk region, Russia's emergencies ministry said.
Kremlin presidential aide Yuri Ushakov said Russia was not ready to hold peace talks with Ukraine for now, given its attack on Kursk.
Ukraine has demanded a full withdrawal of Russian troops from its territory before it sits down for any talks.
Ukrainian forces face a tough battle near Pokrovsk, a transport hub for Ukrainian forces.
Russian troops are about 10km from the outskirts of the city, said Serhiy Dobriak, head of the local military administration.
He said up to 600 people were leaving on a daily basis, and that municipal services could be cut off within a week as Russian forces close in.
Regional governor Vadym Filashkin said a curfew in settlements close to Pokrovsk had been tightened and the situation was "very difficult".
Ukraine's top general said the army was also "doing everything necessary" to defend the eastern city of Toretsk as Russia tries to target Ukrainian supply lines.
Russia said its forces had captured the nearby town of Zalizne.
The war, which has killed tens of thousands and devastated cities across Ukraine, shows no sign of letting up.
Ukraine expects Russia to boost its forces in Ukraine by year's end to 800,000, up from about 600,000, Ukrainian Deputy Defence Minister Ivan Havryliuk told Ukrainian media.
Ukraine has been backed by arms from its allies but is worried that support may drop as the war grinds on.
The United Kingdom reiterated support for Ukraine on Monday, and Indian Prime Minister Narendra Modi is set to visit Kyiv on August 23.
