Two people have been killed after Russian drones struck a border crossing between Ukraine and Moldova, Ukrainian President Volodymyr Zelensky said.
The Starokozache crossing, around 500km (310 miles) south of Kyiv, was closed after the overnight attack. Images from the scene showed several cars left completely scorched, with wreckage and debris strewn across the border post.
Meanwhile, four people, including a child, were killed in the southern Russian city of Novorossiysk in a Ukrainian drone attack, the regional governor said.
Zelensky renewed calls for international support in the wake of the Starokozache crossing attack, saying "the aggression must be stopped here and now before it spreads any further".
A Moldovan driver was also injured, according to the country's foreign ministry.
Moldova has increasingly found itself caught up in the conflict, with Prime Minister Vasile Tofan confirming that 17 drones had struck Moldovan territory in August alone - more than during the whole of last year.
"Those who ignore or downplay these threats - and refuse to name the aggressor - are denying reality," he wrote on social media.
"Russia started this war. Russia alone bears responsibility."
Russia's defence ministry said its forces had shot down 596 Ukrainian drones overnight.
Novorossiysk – in the south of the country on the Black Sea coast - was hit hardest in what governor Veniamin Kondratiev described as a "massive overnight enemy drone attack".
As well as the four deaths, 29 people were injured, and damage was reported to residential buildings, a church and a preschool.
The strikes came a day after Russian President Vladimir Putin spoke to US President Donald Trump by phone about efforts to end the conflict.
The Trump administration has been pressing for direct talks between Russia and Ukraine, with Kyiv saying they could take place this month. The Kremlin, however, has said it is too early to discuss a date or venue.
The call followed talks between US envoys Jared Kushner and Steve Witkoff and Putin in Moscow, before the pair travelled to Kyiv for meetings with Ukrainian President Volodymyr Zelensky.