EU leaders gather in Copenhagen on Wednesday under pressure to boost European defence after a series of Russian incursions into EU airspace, and days after drones targeted Danish airports.
The incursions have become most acute for countries on the EU's eastern flank such as Poland and Estonia. Ten member states have already backed plans for a multi-layered drone wall to quickly detect, then track and destroy Russian drones.
Denmark has beefed up security ahead of the summit, banning all civilian drone flights until Friday and placing heavy restrictions on traffic in Copenhagen.
Despite the high security, there was little evidence of alarm in the centre of the capital ahead of the summit.
Denmark will also host a broader European Political Community summit on Thursday and international allies have lent support to ensure both events pass without incident.
Copenhagen airport, followed by several Danish airports and military sites on the Jutland peninsula, faced drone disruption last week.
Anti-drone and surveillance support has been brought in from Poland, the Netherlands, Finland, Sweden and the US. A German frigate has also docked in Copenhagen.
As host to dozens of European leaders over two days, Denmark will want to fend off any more unwelcome surprises in its air space.
Danish police have not found any evidence that Russia was behind last week's drone disruption, which caused no injuries, but the government has blamed a professional actor. Prime Minister Mette Frederiksen has said there is primarily one country that poses a threat to Europe's security - that is Russia.
Sweden's prime minister Ulf Kristersson also said everything points to [Russia].
Stockholm has loaned a handful of powerful radar systems to its neighbour for the two summits, according to Kristersson.
Ukraine's Volodymyr Zelensky said Kyiv is sending a mission to Denmark for joint exercises to provide Ukrainian experience in drone defence.
German Chancellor Friedrich Merz said ahead of the summit that air space incursions were getting worse and worse and it was reasonable to assume the drones are coming from Russia.
Drones have been seen in recent days over Germany's northern state of Schleswig-Holstein, and flights have been delayed in the past week at Vilnius airport in Lithuania and at Oslo airport in Norway because of drone activity.
We are not at war, but we are no longer at peace either. We must do much more for our own security, Merz told a media event in Düsseldorf this week.
Kremlin spokesman Dmitry Peskov said it was obvious Germany had long been indirectly involved in the war in Ukraine and he rejected unfounded accusations of Russian involvement in last week's disruption in Denmark.
Such is the concern at Russian activity on Europe's eastern flank that NATO met for consultations twice in September under Article 4 of its treaty, first after drones violated Polish airspace and then when Russian MiG-31 war planes entered Estonian air space for 12 minutes.
We have to keep our skies safe, said NATO Secretary General Mark Rutte, who met European Commission chief Ursula von der Leyen in Brussels on the eve of the Copenhagen summit.
The idea of a drone wall was raised a month ago by von der Leyen, and Rutte said it was timely and necessary because in the end we cannot spend millions of euros or dollars on missiles to take out drones which are only costing a couple of thousand dollars.
A senior EU diplomat told the BBC there were still questions over financing the plan and over command and control, but Europe's response to Russia's drone violations in Poland had led to some serious soul-searching: We have to be more agile and find better tools.
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