He added that Romanian forces were constrained as they could not fire into Ukrainian airspace to destroy the drone before it crossed the border.
“Ukraine is at war, but Romania is at peace,” he said. “We cannot launch a projectile into Ukrainian airspace.”
Romania described the strike as a “grave escalation” and summoned the Russian ambassador.
Nicușor Dan, the country’s president, convened an emergency meeting of the national security council for Friday morning to discuss the response, saying he would “order proportionate measures”.
“Romania is a Nato member state and will not accept, in any way, the war of aggression waged by Russia against Ukraine to be transferred on to its citizens,” said Mr Dan.