Satellite images reveal another mass grave near Mariupol.

The news comes after U.S. President Donald Trump said he would impose tougher sanctions on Moscow once European allies cease purchasing Russian oil.

Ukraine's Air Force said Russian forces launched 113 Shahed-type attack and decoy drones overnight.

The Polish prime minister said that the drone had been operating near several government buildings in the Polish capital, including the Belweder palace, which serves as one of the official presidential residences as well as a guest house for international dignitaries.

Ukrainian forces struck the Saratov oil refinery overnight on Sept. 16, causing explosions and a fire at the facility, the General Staff reported.

World leaders will gather in New York starting Sept. 22 for the U.N.'s annual high-level session.

"If you keep postponing applying sanctions any further, then the Russians will be better prepared," President Volodymyr Zelensky said.

The Sept. 8 attack targeted command posts of Russia's "Center" group of forces and the 41st Combined Arms Army, whose units operate in the Pokrovsk sector, Ukraine's military said.

"I guarantee you that if Europe put on substantial secondary tariffs on the buyers of Russian oil, the war would be over in 60 or 90 days," U.S. Treasury Secretary Scott Bessent said.

The number includes 910 casualties that Russian forces suffered over the past day.

Russia has revived barter in its foreign trade for the first time since the 1990s, exchanging goods such as grain and flax seeds for Chinese cars and construction materials in an effort to evade sanctions, Reuters reported Sept. 15.

Regional Governor Ivan Fedorov said the city had sustained at least 10 strikes amid the attack which targeted both homes and "non-residential buildings."

The Kirishi refinery is one of the largest in Russia and has a processing capacity of over 17 million tons of oil per year. A fire broke out at the facility during a Ukrainian drone attack, Leningrad Oblast Governor Alexander Drozdenko claimed.

"Eastern Sentry is not just a new initiative – it is a clear signal: NATO’s borders are inviolable, and the security of our citizens remains a priority," Poland's General Staff wrote on X.

Ukraine's Air Force said Russian forces launched 84 Shahed-type attack and decoy drones and three S-300 missiles overnight.

Capturing the city of Kupiansk serves as Russia's main goal in Kharkiv Oblast, operational-strategic command "Dnipro" spokesperson Oleksiy Belsky said on Sept. 15, amid Russia's attempted infiltrations into the key Ukrainian stronghold.