The Ukraine Military on Tuesday morning claimed Russia has initiated an air attack on Kyiv, the capital of the war-torn country, media reports said.
The military said it was engaging in air defence systems to thwart the attack.
No victim or destruction has been reported, said Serhiy Popko, the head of Kyiv's military administration.
Ukraine has also claimed all incoming drones were shot down.
The reported attack, which would be the sixth on the capital this month, came a day after Russia warned Ukraine of "tough retaliatory measures" following a drone attack on Moscow.
Russian Foreign Ministry spokeswoman Maria Zakharova on Monday called a recent drone attack on objects in Moscow an act of international terrorism.
Moscow Mayor Sergei Sobyanin said that at about 4:00 a.m. Moscow time (01:00 GMT) on Monday, drone strikes on two non-residential buildings had been recorded in the Russian capital, adding that there was no serious damage or casualties.
The Russian Defense Ministry later confirmed that the attack had been thwarted, saying that two Ukrainian drones had been suppressed by means of electronic warfare and crashed.
"It is an act of international terrorism," Zakharova told the RTVI broadcaster, commenting on the attack.