NATO on Tuesday condemned Russia for violating Estonian airspace last week. It said the incident was part of a pattern of recent actions that were "escalatory, risk miscalculation, and endanger lives."
"Russia should be in no doubt: NATO and Allies will employ, in accordance with international law, all necessary military and non-military tools to defend ourselves and deter all threats from all directions," the alliance's North Atlantic Council said in a statement.
Estonia said on Friday that three Russian MiG-31 fighter jets had entered Estonian airspace without permission and stayed for a total of 12 minutes before they were forced to withdraw in an episode that Western officials said was designed to test NATO's readiness and resolve.
The Security Council convened on Monday to discuss the issue. NATO consultations were due to take place on Tuesday. The incident occurred just over a week after more than 20 Russian drones entered Polish airspace, prompting NATO jets to shoot some of them down.
British Foreign Minister Yvette Cooper warned on Monday that Russia's incursions into NATO territory risked triggering an armed conflict, drawing an immediate rebuke from Moscow, which dismissed Europe's concerns as groundless and hysterical.
NATO confronts Russia at UNSC
"Your reckless actions risk direct armed confrontation between NATO and Russia. Our alliance is defensive, but be under no illusion we stand ready to defend NATO's skies and NATO's territory," Cooper said.
"If we need to confront planes operating in NATO space without permission, then we will do so."
Cooper's comments were echoed by other Western ministers in the Security Council, who suggested the multiple incidents could not be considered an accident.
Previous US ambassador to the UN, Dorothy Shea, told the UNSC that Russia's previous violation of Poland's airspace was disrespectful to US mediation efforts.
"These actions, now with the addition of violating the airspace of a US ally – intentionally or otherwise – show immense disrespect for good-faith US efforts to bring an end to this conflict," Shea said.
US Envoy to the UN Michael Waltz also told the Security Council meeting to discuss accusations of a Russian airspace violation.
"I want to take this first opportunity to repeat and to emphasize the United States and our allies will defend every inch of NATO territory," he said in his first appearance since becoming ambassador.
Russia's deputy ambassador to the UN, Dmytry Polyanskiy, said there was no evidence backing their claims and accused European powers of levying "baseless" accusations.
"We won't be partaking in this theater of the absurd," he said. "When you decide that you want to engage in a serious discussion about European security, about the fate of our common continent, about how to make this continent prosperous and secure for everybody, we'll be ready."
Last week, top Kremlin aide Dimitry Peskov said that Russia was effectively at war with NATO.
"NATO is at war with Russia," Peskov said, as reported by Russian state agency TASS. "It’s evident, and it doesn’t need any additional confirmation."
He added that NATO was "de facto taking part in this war" with Ukraine by providing support to Kyiv.
Additionally, following drone attacks on Kyiv last week, Russian Foreign Ministry Spokeswoman Maria Zakharova alleged that the EU and NATO "are the pulse of destabilization and the spread of terrorism in Europe."
Corinne Baum contributed to this report.