Croatian PM Andrej Plenkovic on Friday sent a letter to leaders of EU countries, of European institutions, and NATO Secretary General, informing them of the crash of an unmanned aerial vehicle in Zagreb, and asking for closer cooperation between the EU and NATO so that such incidents would not happen again.

In order to deal effectively with such situations, it is important to continue strengthening our mechanisms for exchanging information and for rapid coordinated responses. I therefore invite you to share with us all information you may have about this incident, reads the letter sent by Plenkovic to EU heads of state or government, European Council President Charles Michel, European Commission President Ursula von der Leyen, High Representative of the EU for Foreign Affairs and Security Policy Josep Borrell, and NATO Secretary General Jens Stoltenberg.

In the context of the Russian aggression against Ukraine and the war fought there, this serious incident requires closer cooperation between EU members and NATO allies, the letter said.

In the letter, Plenkovic said that the unmanned aerial vehicle crashed near the centre of Zagreb, in a park near a student residence hall which houses 4,500 students, and that the impact produced a large crater, damaging several cars, but that there were fortunately no casualties.

The investigation has so far established that the aerial vehicle was a medium-range military reconnaissance drone with an operational range of one thousand kilometres, a TU-141 Strizh, which was made in the former Soviet Union.

It entered Croatia’s airspace from Hungary.

We still do not know for certain where the aerial vehicle was launched from, but according to an analysis of its trajectory, it came from the Ukrainian territory. What we know is that it entered the EU airspace from Ukraine and crossed the Romanian and Hungarian airspace on its way to Croatia, Plenkovic said in the letter.

It is not known who launched the drone nor whether its trajectory was intentional or it was out of control, he added.

The aerial vehicle that crashed was a reconnaissance drone, but tomorrow it could be an armed one, so it is key that we establish mechanisms for detection and defence that will prevent such aerial vehicles from threatening our cities without being detected and neutralised, the letter said.