Croatian prime minister on March 12 urged closer cooperation within NATO after a military drone, which he said had been launched from Ukraine, crashed in Zagreb.
The Soviet-era Tu-141 reconnaissance drone crashed in the Croatian capital late on March 10, damaging around 40 parked vehicles, but no one was injured.
Officials said earlier that it entered Croatia’s airspace from Hungary, having flown in from Romania.
All three countries are NATO members.
“According to what we know now, it was obviously launched on Ukraine’s territory”, Prime Minister Andrej Plenkovic told reporters on March 12.
“We don’t know in whose possession it was,” he said, adding that both Ukraine and Russia had said it was not theirs.
Plenkovic, speaking at the site of the incident, said he had sent a letter to his EU counterparts and NATO secretary-general Jens Stoltenberg over the incident.
“Whether it was accidental, a mistake or intentional, we do not know at this moment.”
The incident “points to the need for closer cooperation within NATO”, he said.
The drone had flown undisturbed over the alliance’s three member states, he said, adding: “We cannot tolerate such a situation any more.
“It was a very clear threat that requires a reaction.”
According to officials, the drone flew over Hungary and Croatia before crashing.
Local security experts immediately labelled the incident a NATO failure. President Zoran Milanovic said on March 11, “It’s a matter of NATO joint command.”
On March 11, a NATO official said that the military alliance’s “integrated air and missile defence tracked the flight path of an object which subsequently crashed in Zagreb”.
Later on March 12, Stoltenberg tweeted that he “spoke with Croatia’s PM @AndrejPlenkovic on yesterday’s drone incident in Zagreb.
“We agreed to stay in close contact and work together to establish the facts,” he wrote.
The drone crashed around 11pm (2200 GMT) on March 10 in a park close to the Jarun lake.
Some 6km from the city centre, the site is just next to a students residence with some 4,500 people and residential buildings.
The 14m drone, weighing more than six tonnes, still has to be dug out from a crater it made when crashing.
Zagreb is about 550km flying distance from the border with Ukraine.
