Russia and Ukraine claimed to have downed each other's drones over the Black Sea on Monday, with both sides apparently devoting increasing attention to developing and using unmanned aircraft in their more than two-year-old war.
Russia's Defence Ministry, writing on the Telegram messaging app, said its air defence units had intercepted six Ukrainian drones attempting to carry out a "terrorist attack".
The governor of Russia's border region of Belgorod, Vyachelsav Gladkov, wrote on Telegram that defence units had downed 19 airborne targets and Ukrainian shelling of the region had injured 10 people.
A spokesperson for Ukraine's Air Force, Illya Yevlash, told national television that Ukrainian forces had downed a Russian "Forpost" drone which he described as one of the most sophisticated and costly in Moscow's arsenal.
"It's not often we get a target like that, but we did it - one of the most expensive Forpost attack drones," Yevlash said, estimating its value at $8 million.
Military publications describe the Forpost as a Russian version of a reconnaissance drone used for decades by Israel and capable of carrying our surveillance at an altitude of 5 km (3 miles) continuously for 16 hours.
Natalia Humeniuk, a spokesperson for Ukraine's southern group of forces, said Russia was using the drones more frequently after Ukrainian air defence units proved successful at shooting down at least two A-50 surveillance aircraft.
"In the past 24 hours, we observed more than 200 reconnaissance drones in our area of responsibility from Odesa to Zaporizhzhia," she told national television.
"They were a bit fewer today, but the enemy carries on with reconnaissance. They clearly need to compensate for the A-50."
Ukrainian President Volodymyr Zelenskiy again stressed the importance of boosting domestic manufacture of drones after setting a 2024 production target of one million.
"The war demands that our defence industrial complex produce as many as needed in as timely a fashion as is needed," Zelenskiy said in his nightly video address.
"It is clear that drones in this war will be one of the decisive words for victory and it must be a Ukrainian word, Ukrainian drones, a Ukrainian victory," he said. "We need more drones and more effective Ukrainian drones."