EU leaders are meeting in Copenhagen under pressure to boost European defence after a series of Russian incursions into EU airspace, and days after drones targeted Danish airports.
Danish Prime Minister Mette Frederiksen told reporters that from a European perspective there is only one country... willing to threaten us and that is Russia, and therefore we need a very strong answer back.
The incursions have become most acute for countries on the EU's eastern flank such as Poland and Estonia.
A number of 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 for the summit, banning all civilian drone flights until Friday and placing heavy restrictions on traffic in Copenhagen.
Denmark is also hosting 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.
Ten allies are providing anti-drone and surveillance support, according to Denmark's military, which has highlighted an increased presence of foreign troops and equipment. Among the countries contributing are Poland, the UK, 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, but Frederiksen linked it explicitly to other hybrid attacks such as Russia's drone incursion over Poland.
It was part of a pattern that had to be viewed from a European perspective, she told reporters on Wednesday.
The war in Ukraine is very serious. When I look at Europe today I think we are in the most difficult and dangerous situation since the end of the Second World War - not the Cold War any more.
Sweden has loaned powerful radar systems to its neighbour for the week and 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; however, Europe's response to Russia's drone violations had led to serious soul-searching: We have to be more agile and find better tools.
Denmark's call for a strong, united response to Russia's aggressive maneuvers encapsulates the heightened tensions and urgent challenges faced by European nations as they navigate a complex security landscape.
