These are the main developments as the Russian invasion of Ukraine enters its 525th day.

Fighting

• The Russian military said anti-aircraft units thwarted a Ukrainian “terrorist attack” and downed drones targeting Moscow, but that one drone struck a high-rise tower that was hit earlier in the week. No casualties were reported.
• Russia said it had repelled an overnight Ukrainian drone attack aimed at its patrol boats in the Black Sea.
• Mykhailo Podolyak, an adviser to Ukrainian President Volodymyr Zelenskyy, told the Reuters news agency that Kyiv did not attack and would not attack civilian vessels in the Black Sea, calling Russian claims “fictitious”.
• Drones struck populated areas in the Ukrainian city of Kharkiv, destroying two floors of a college dormitory, according to local officials. Kharkiv Mayor Ihor Terekhov said there had been three separate attacks on Ukraine’s second-largest city.
• Andriy Yermak, the head of the Office of the President of Ukraine, said Russia is targeting residential areas and medical centres in Kherson. Yermak said shelling on the Kherson City Clinical Hospital left a doctor dead and a nurse injured.
• Ukraine thwarted an overnight attempt by a Russian saboteur group to cross its northern border, Interior Minister Ihor Klymenko wrote on the Telegram messaging app. “Last night, in the Chernihiv region, border guards stopped an attempt by an enemy saboteur-reconnaissance group to cross the state border of Ukraine within the Semenivka community,” he said.
• Reporting from Donetsk in eastern Ukraine, Al Jazeera’s Ali Hashem said the city was on the receiving end of “continuous” shelling. “You can hear explosions every now and then. This comes as a pattern over the past few days.”
• Russia downed a drone over a district of Sevastopol, the city on the Crimean Peninsula that is home to the country’s Black Sea naval fleet, according to the Moscow-installed local governor.
• Pro-Ukrainian residents in Russian-annexed Crimea have been “systematically” trying to attack Russian military bases with Molotov cocktails, a Ukrainian intelligence report said.
• Ukraine’s Deputy Defence Minister Hanna Maliar said Russia is “quite persistently” trying to stop Kyiv’s advance in the direction of Bakhmut, but has been unsuccessful.
• The United Nations Educational, Scientific and Cultural Organization (UNESCO) said that as of July 26, at least 274 cultural sites have been damaged during Russia’s war in Ukraine.

Diplomacy

• Ukraine’s foreign ministry summoned Poland’s ambassador to Kyiv, saying comments made by the Polish presidential foreign policy adviser, Marcin Przydacz, were “unacceptable”. Przydacz had said Ukraine “should start appreciating the role that Poland has played for Ukraine in recent months and years”.
• Saudi Arabia is preparing to host a summit to discuss Zelenskyy’s plan for peace in his country amid the ongoing Russian invasion, according to a senior official in Kyiv.
• The United States has been told that Russia is prepared to return to talks on a deal that had allowed the safe Black Sea export of Ukrainian grain, but “we haven’t seen any evidence of that yet,” US Ambassador to the UN Linda Thomas-Greenfield said.
• Yermak, the head of the Ukrainian president’s office, said that Kyiv is intensifying work on the implementation of the Ukrainian Peace Formula and preparing for this year’s Global Peace Summit.

Military

• Poland’s defence ministry said it would increase the number of troops at its border with Belarus after two helicopters from Belarus violated Poland’s airspace. Belarus’s defence ministry denied that there had been any incursion, saying the claim was “farfetched and made by the Polish military and political leadership to justify the build-up of forces and means at the Belarusian border.”
• White House National Security Council spokesperson John Kirby said the US is not aware of any specific threat posed to Poland or other NATO allies by the presence of Russia’s Wagner Group forces in Belarus.
• Russian Defence Minister Sergei Shoigu said that Moscow is ready to help improve Algeria’s combat readiness in a meeting with the chief of staff of Algeria’s armed forces.