Polish and other NATO jets scrambled on September 20 as Russia launched another massive drone and missile attack on Ukraine.
The wave of overnight strikes came shortly after NATO countries voiced outrage at a Russian incursion into Estonian airspace the previous day, as well as recent Russian drone incursions into Poland and Romania.
"Polish and allied aircraft are operating in our airspace, while ground-based air defense and radar reconnaissance systems have been brought to the highest state of readiness," Poland’s military Operational Command said in a post on X.
SEE ALSO: Russia's Latest Airspace Violation Raises Alarms With NATO, AlliesThe operation, which lasted around 90 minutes, underlined the heightened state of alert in NATO countries following the Russian incursions.
Later on September 20, Estonia's Defense Ministry released a map showing the flight path of three Russian MiG-31 fighter aircraft the previous day.
"The violation took place over the Gulf of Finland," it said, adding that the Russian jets flew parallel to the state border from east to west, entering Estonian airspace to a depth of less than 10 kilometers.
Moscow has denied the violations, and also denied that its drones entered Polish airspace intentionally in the previous incident.
Amid the ongoing diplomatic fallout, the Russian attacks on Ukraine included 579 drones, 32 cruise missiles, and 8 ballistic missiles, Ukraine’s air force reported.
Ukrainian President Volodymyr Zelenskyy said three people were killed and dozens injured.
"The enemy's target was our infrastructure, residential areas, and civilian enterprises. In Dnipro, a direct hit of a rocket with cluster munitions on a high-rise building was recorded,” he said.
Zelenskyy repeated calls made following the September 9 drone incursions for NATO to work with Ukraine on joint air defenses. “For a reliable shield we must act together,” he said.
NATO on September 12 said it had launched a new "activity," dubbed Eastern Sentry, that would deploy additional military hardware from Britain, Denmark, France, and Germany to countries on its eastern flank.
But the alliance has resisted calls for an air umbrella within Ukraine.
Residents react as they stand near a residential building damaged during a Russian missile strike on the Ukrainian city of Dnipro on September 20.
The head of the Dnipropetrovsk region, Serhiy Lysak, said there were 26 victims in the eastern city of Dnipro.
“Fourteen are in the hospital, the rest will recover at home. A 55-year-old man is in serious condition. He has burns on 70 percent of his body. Doctors are fighting for his life," he said.
The Ukrainian Air Force said air defenses had intercepted the vast majority of incoming fire, highlighting the use of US-made F-16 jets against Russian cruise missiles.
Meanwhile, the Russian Defense Ministry said the country’s air defenses had shot down 149 Ukrainian drones overnight, in a variety of locations including the Rostov, Saratov, Bryansk, and Samara regions, and over Russian-occupied Crimea.
A source in Ukraine's Security Service (SBU) told RFE/RL's Ukrainian Service that a number of oil pumping stations were put out of action.
Ukraine’s military said it had struck oil facilities in both the Saratov and Samara regions, near Kazakhstan.
The head of the Samara region, Vyacheslav Fyedorishchev, said four people were killed in a Ukrainian attack.
The head of the Saratov region, Roman Busargin, wrote on Telegram that windows were blown out of two housing blocks and one woman was hospitalized.
While Russia regularly targets civilian infrastructure including housing, hospitals, and schools, Ukraine has waged a targeted campaign against Russia’s oil refineries, reportedly taking out nearly a fifth of Russia’s capacity.
Battlefield claims by either side could not be independently confirmed.