Mr Ischinger argued that the energy spent on the row should be used to end Russia’s war in Ukraine.
“1945 problem-solving will not solve 2026 problems,” he warned, saying outdated structures risk losing legitimacy.
Moscow claimed Ukraine attempted to attack Mr Putin’s Valdai residence in western Russia with 91 drones, all of which it said were shot down.
Ukrainian media reported that hypersonic Kinzhal missiles were among the weapons used.
“Good evening, America. Eleven months ago, I inherited a mess, and I’m fixing it,” said Mr Trump.
EU leaders will meet in Brussels on Thursday, aiming to agree on how to fund Ukraine’s economic and military needs in the coming years.
Russia is not looking to rejoin G7, President Vladimir Putin said during a visit to India on Thursday.
The press was not allowed to attend.
The UN chief is attending the summit to push for economic and climate action.
According to media reports, the draft agreement from Washington envisions Ukraine ceding territory and making additional concessions.
