More NATO countries will move troops and fighter jets eastwards after more than a dozen drones entered Polish airspace on Wednesday.
Denmark, France, and Germany have joined a new mission to bolster the military alliance's eastern flank. Other NATO allies are expected to take part later.
Tensions have been high across Europe since Poland accused Russia of an unprecedented incursion. Some of the 19 drones that entered Polish territory were shot down, while others crashed into fields and even a house in eastern Poland.
Warsaw said the incursion was deliberate, but Moscow downplayed the incident, saying it had 'no plans to target' facilities in Poland.
Drones and missiles have occasionally veered into countries bordering Ukraine during Russia's full-scale invasion, but this was the most serious incident of its kind since the war began in February 2022.
Polish Prime Minister Donald Tusk said it was the closest we have been to open conflict since World War Two. Denmark will contribute two F-16 fighter jets to support Poland's air defense, as well as a warship, its defense ministry said.
Danish Prime Minister Mette Frederiksen emphasized that vigilance is crucial, stating: Putin will stop at nothing, and he is testing us. France is providing three Rafale fighter jets, while Germany has pledged four Eurofighters.
The UK has committed to strengthening the Eastern Sentry operation, with further details expected soon.
On Friday, European countries and the US backed Poland during an urgent UN Security Council session discussing the incursion. Acting US Ambassador to the UN, Dorothy Shea, reassured that the US stands firmly with NATO allies in the face of alarming airspace violations.
Despite this, Kremlin spokesman Dmitry Peskov dismissed accusations of targeting Poland, suggesting there had been a pause in peace negotiations, attributed to external pressures from Ukraine's allies.
