NATO allies condemned Russia's violation of Estonia's airspace -- the third provocative intrusion by Kremlin air assets in recent days -- with the Western military alliance setting a meeting of its North Atlantic Council to discuss the deepening crisis.

"I've just spoken with the Estonian PM Kristen Michal about the Russian airspace violation today," NATO chief Mark Rutte saidon social mediaon September 19.

"NATO's response...was quick and decisive," he added, referring to the deployment of alliance jets after the small Baltic nation reported that three Russian MiG-31 fighter aircraft entered its airspace.

Colonel Martin O'Donnell, spokesman for NATO's Supreme Headquarters Allied Powers Europe, said that "NATO quickly responded under Eastern Sentry, scrambling Italian F025 fighter jets based in Estonia."

SEE ALSO:

NATO Launches 'Eastern Sentry' To Bolster Defenses Near Russia

"Sweden and Finland also scrambled their quick-reaction aircraft," O'Donnell said.

Russia's Defense Ministry later denied its aircraft had violated Estonian airspace, saying the planes were on a "scheduled flight...in strict compliance with international airspace regulations."

No Flight Plans, Transponders 'Switched Off'

The Estonian military said the jets remained in national airspace for 12 minutes in the Vaindloo Island area without permission.

"The fighter jets did not have flight plans, and their transponders were switched off," the military said. "At the time of the airspace violation, the fighter jets did not have two-way radio communication with Estonian air traffic control."

Michal said his government hadrequested the invokingof NATO's Article 4, which sets a mandatory meeting of alliance members but is short of the more seriousArticle 5.

Estonia's Foreign Ministry also summoned Russia's charge d'affaires to "lodge a protest and deliver a note of concern" over the incident.

"I would say that NATO's air defense worked -- the planes left, forced the Russian planes to leave. But to be in Estonian airspace for such a long time is, of course, at least malice, if not a planned operation," Michal said.

SEE ALSO:

Congress Wants To Label Russia A Terrorism Sponsor. Will It Happen?

In response, NATO said it would conduct a meeting of its North Atlantic Council -- the principal political decision-making body within NATO -- early next week to discuss Russia's actions, although a date was not announced.

US President Donald Trump told reporters he would soon be briefed on the reported Russian airspace violation.

I dont love it...I dont like when that happens. It could be big trouble, but Ill let you know later, he said.

EU foreign policy chief Kaja Kallas called Russia's action an extremely dangerous provocation.

SEE ALSO:

China's Defense Universities Help Russia Offset Sanctions And Export Controls, New Research Shows

The incident follows recent incursions by Russian drones in Poland and Romania which -- like Estonia -- are members of NATO and the European Union. Russia had launched the drones toward Ukraine as part of its full-scale invasion of that country.

Luke Coffey, a senior fellow at the Hudson Institute in Washington, told RFE/RL that I do expect them [Russian airspace violations] to continue until there's some sort of forceful act -- until NATO makes the conditions...to the point where any risk that Russia might have to incur by doing these incursions isn't worth it.

I think this is just part of the broader strategy by [Russian President Vladimir] Putin to defy Trump and at the same time make division inside the alliance more noticeable, Coffee said.

I think it's going to continue. NATO should implement a very robust policy of Baltic air defense, not Baltic air policing. We have moved beyond the need for patrolling the skies. We now need to defend the skies, he added.

NATO on September 12 announced an effort to bolster defenses in its so-called eastern flank, launching an "activity," dubbed Eastern Sentry, that would deploy additional military hardware from Britain, Denmark, France, and Germany to deter potential Russian aggression.

Zelenskyy Calls Airspace Violation 'Outrageous'

Ukrainian President Volodymyr Zelenskyy condemned Russia for intensifying tensions the jets violated Estonian airspace, calling the action "outrageous" and "destabilizing."

"These are not accidents. This is a systematic Russian campaign directed against Europe, against NATO, against the West. And it requires a systemic response," Zelensky wrote on social media.

"Strong action must be taken," he added.

European Commission President Ursula von der Leyen mentioned the earlier drone incursions whileannouncing proposalsfor the EUs latest sanctions package.

Again and again, President Putin has escalated, and in response, Europe is increasing its pressure, she said.