Nato's red lines could turn Ukraine into no man's land

The intrusion of a significant number of Russian drones over Poland last week was already focusing minds in Nato, not least on the thorny question of where it draws its “red lines”, when another such incursion took place at the weekend.

- MARK ALMOND

Last Wednesday, 19 Russian drones were found to have crossed over into Polish airspace, some having travelled hundreds of miles inland, before a handful were shot down by local and Nato aircraft. It marked an unsettling escalation of tensions between Russia and Europe, and prompted Poland's prime minister to declare military conflict on the continent "closer than at any time since the Second World War".

Only a few days later, on Saturday, another drone violated airspace over Romania, dispelling any lingering doubt that Vladimir Putin was testing Europe's resolve. Two Romanian F-16s were sent to shadow the military craft for about an hour, but did not shoot it down, leaving it to cross back into Ukraine to wreak havoc there.

Ukraine's president, Volodymyr Zelensky, said the incursion could not be a mistake and was "an obvious expansion of the war by Russia". Kaja Kallas, the EU's foreign policy chief, called the incident "yet another unacceptable breach of an EU member state's sovereignty". The UK has since summoned the Russian ambassador to explain his country's actions.

Russia said its drones went astray because they were jammed. For now, Nato has limited its response to "unreservedly condemning these reckless actions". So what would it take for a member to invoke Article 5, which provides that an "armed attack against one" Nato member "shall be considered an attack against them all"?