US plans to talk to Ukrainian armed forces forces to find out more about the entry into Russian territory, White House spokeswoman Karin Jean-Pierre said today, quoted by Reuters and BTA.
Jean-Pierre emphasized that the US had no prior information about the attacks.
Russia said today that it is fighting fierce battles against Ukrainian forces that have entered the territory of Russia's Kursk region.
The acting governor of the Kursk region, Alexei Smirnov, said he has declared a state of emergency in the region he oversees.
The Russian National Guard said it is stepping up security measures around the Kursk nuclear power plant and its four reactors.
Russian President Vladimir Putin described the entry into Russian territory as a provocation.
Chief of the General Staff of the Russian Armed Forces, Valery Gerasimov, reported to Putin that Russian forces had halted an attack by about a thousand Ukrainian soldiers and that Ukrainian forces would be pushed back to the Russian-Ukrainian border.
In his daily address, Ukrainian President Volodymyr Zelensky congratulated the Ukrainian forces for their courage, without specifically mentioning the situation in the Kursk region, AFP reported.
Meanwhile, prominent Russian military correspondent Yevgeny Poddubny survived a Ukrainian drone attack in Russia's Kursk region yesterday and is in the intensive care unit of a local hospital, Reuters reported, citing BTA, citing the television station he works for Poddubny.
"Russia-24" said in the Telegram communication application that Poddubny was wounded by a Ukrainian drone while on duty in the Kursk region, where the Russian armed forces said they were fighting about a thousand Ukrainian soldiers who had entered Russian territory.
"Military correspondent Yevgeny Poddubny is conscious. He is currently in intensive care. He is getting the care he needs," the Russian Ministry of Health said.
"Russia-24" said that Poddubny, who is one of the most popular correspondents covering the conflict in Ukraine, had passed on information about the situation in the Kursk region hours before he came under fire.
Poddubny also covered the conflict in Syria.
Russia's Investigative Committee said it would investigate who was responsible for the attack and that Poddubny would be awarded a reward.