A Russian drone hit a block of flats in Romania, causing a fire and injuring two people, Romanian officials say.
Friday's incident in the eastern town of Galați, near the border with Ukraine, was condemned by Romania's fellow members of Nato and the EU. Ukraine said it proved again that Russia posed "a real threat" to Europe.
Romanian President Nicușor Dan said the drone was likely hit by Ukrainian air defences over Kyiv's territory, altering its trajectory. Russian President Vladimir Putin later questioned whether the drone was Russian.
Drones fired by Russia have strayed into Romania a number of times during the four-year war with Ukraine, but it is the first time Romanians have been hurt.
Romania's emergency situations authority said the drone's entire explosive payload detonated and caused a fire on the 10th floor of the residential building.
Two people with abrasions required medical treatment and were taken to the Galați County Emergency Clinical Hospital. About 70 people were evacuated as the fire was put out.
Romania's defence ministry said two F-16 fighter jets were scrambled after the drones were detected. Brig Gen Gheorghe Maxim said the army had only four minutes from when the drone was detected to the moment of impact.
The ministry added in a later update that it appeared the "entire load" of the Geran 2 drone - also known as a Shahed 136 - had exploded on impact.
Gen Maxim said Romanian forces were under significant constraints, as they could not fire munitions that violated Ukrainian airspace. "Ukraine is at war, but Romania is at peace. We cannot launch a projectile into Ukrainian airspace," he said.
Romania's military has sought to reassure the public that it was not an attack on the country but rather "a conflict at our border, with consequences for the local population".
Speaking during a visit to Galați later on Friday, President Dan said the drone was likely hit while over Ukraine, apparently by Ukraine's air defences.
"There was a group of 43 drones coming from the east. Some were shot down over Ukraine, and one was hit above the [Ukrainian] city of Reni, which altered its trajectory."
Dan also said his administration would expel the Russian consul in the Black Sea port of Constanța and shut down the consulate. Moscow said it "won't take long" to respond.
President Dan also convened an emergency meeting of Romania's Supreme Defence Council, describing the Russian drone strike as "the most serious incident to have affected Romanian territory since the start of Russia's war of aggression against Ukraine".
The country's foreign ministry said Bucharest had "requested measures to accelerate the transfer of anti-drone capabilities to Romania" from Nato.
The alliance's secretary general, Mark Rutte, said he had spoken to President Dan and told him the alliance "stands ready to defend every inch of allied territory".
"We will continue to enhance our readiness to deter and defend against any threat, including from drones," Rutte added.
European Commission President Ursula von der Leyen wrote on X: "Russia's war of aggression has crossed yet another line".
"As we continue strengthening our security and deterrence, especially on our Eastern border, we will keep increasing the pressure on Russia," she added.
Ukraine's Foreign Minister Andriy Sybiha said the incident "proved once again that Russian aggression poses a real threat to the Black Sea region".
He urged other countries to strengthen support for Ukraine and increase pressure on Russia "to restore peace and security in the region".
In a post on social media on Friday evening, Ukrainian President Volodymyr Zelensky said he had expressed support for Romania during a phone call with President Dan.
"We will be in constant communication with Romania and will continue to work together to protect life from all potential Russian threats," Zelensky added.
UK Prime Minister Sir Keir Starmer said the drone hit was a "serious violation" of Nato airspace, and added that the UK stood "shoulder to shoulder with Ukraine, with Romania, and with all our Nato allies in the face of continued Russian aggression".
Other European politicians also condemned the incident, including the French foreign minister, the US Ambassador to Nato and German Chancellor Friedrich Merz.
At a news briefing later on Friday, President Putin said he had only just heard of the incident, suggesting the drone wreckage should be handed over to Russia for an "objective investigation".
He also recalled recent cases of Ukrainian drones straying into a number of EU countries.
Putin launched a full-scale invasion of Ukraine in February 2022 and several Nato countries have witnessed drone incursions since then.
Poland blamed Russia for a drone strike on a field in the village of Osiny 130km (80 miles) south-east of Warsaw last August, and then shot down two suspected Russian drones over its territory the following month.
At the time, Polish Prime Minister Donald Tusk said he had involved Article 4 of the Nato Treaty, which requires members of the alliance to hold urgent consultations.
For Romania and its Nato allies, the border areas near the River Danube - including Galați - are extremely difficult to defend when Russian drones attack the Ukrainian ports of Reni and Izmail.
Romania's defence ministry says that since the start of the war in Ukraine, drone fragments have been found on Romanian territory on 47 separate occasions, 12 of them this year alone.
Last month, fragments of a Russian drone landed on the outskirts of Galați, after a drone was detected across the Ukrainian border near the town of Reni. Nato fighter jets were authorised to target drones at the time but could not fire on one that had been tracked by radar as it did not breach Romanian airspace.
Nato's secretary general said on Friday the Galati incident "showed yet again that the implications of [Russia's] illegal war of aggression don't stop at the border".
In recent months, Nato member states in the Baltics have also faced a series of incidents involving long-range Ukrainian drones that Kyiv says went off course after being jammed by Russian signals.
