"I told the NATO secretary general that this is a serious incident and that we in Estonia are understandably worried about it," Ratas was quoted by spokespeople as saying. "Thank God that, as far as we know, no one was injured as a result of the incident."

The prime minister asked Stoltenberg for NATO to take Tuesday's incident very seriously and quickly determine the details about what happened, adding that there was no doubt that Estonia's institutions would contribute to these efforts in every way.

"The secretary general confirmed to me that NATO as well as allies closely connected to air policing will do the same," Ratas continued. "NATO's air policing mission is an important part of guaranteeing the security of Estonia and the whole alliance."

Ratas and Stoltenberg also discussed the results of July's Brussels Summit and agreed that increasing the alliance's defense expenditures is important. Estonia continues to contribute more than 2% of its GDP to national defence.

Luik speaks with Spanish colleague

Minister of Defence Jüri Luik (Pro Patria) also spoke with Spanish Minister of Defence Margarita Robles Fernández about the incident, according to a ministry press release.

Robles expressed regret that the incident took place during the NATO Baltic Air Policing mission.

"We discussed the details of the incident and agreed to work closely in the ongoing search of the missle as well as on the investigation," Luik said.

The two colleagues agreed that NATO's Baltic Air Policing mission serves a key role in securing the alliance's airspace.