New fragments of a drone similar to those used by the Russian military were found on Romanian soil, the defense ministry said on Saturday, and President Klaus Iohannis said this indicated an unacceptable breach of Romania's air space had occurred.
In a statement, Iohannis said he had informed NATO Secretary General Jens Stoltenberg about the pieces of drone - the second to crash in Romanian territory this week - and that Stoltenberg reiterated the alliance's complete solidarity with Romania.
"The identification by Romanian authorities on Romanian territory near the border with Ukraine of new drone fragments ... indicates an unacceptable breach occurred of the air space of Romania, a NATO state, with real risks to the security of Romanian citizens in the area," Iohannis said.
"I firmly condemn this incident caused by Russian attacks on Ukrainian Danube river ports."
The attacks on Ukraine's river ports, just hundreds of meters from the Romanian border, have increased security risks for NATO whose members have a mutual defense commitment.
The US State Department said earlier this week it would rotate additional US F-16 fighter jets to bolster NATO's air policing mission in Romania.
The defense ministry said Romania's Naval Forces deployed search teams after local authorities alerted them to suspected drone fragments discovered 2.5 km southeast of the village of Plauru, across the Danube from the Ukrainian port of Izmail.
The military has secured the area and the fragments will be analyzed, it said in a statement.
Since July, when Moscow abandoned a deal that lifted a de facto Russian blockade of Ukraine's Black Sea ports, it has repeatedly struck Ukrainian river ports that lie across the Danube from Romania.
Ukraine is one of the world's biggest grain exporters and Romania's Black Sea port of Constanta is now its largest alternative export route, with grains arriving by road, rail or barge across the Danube.
Ukraine had said on Monday that drones detonated in Romania during an overnight Russian air strike on Ukraine's Izmail, but Romanian officials initially denied the reports before finding fragments on Wednesday.
