On Monday, Finland's border guard reported that a Russian plane had intruded on the country's airspace. Now, it is announced that three more Russian planes are suspected of trespassing.
According to a press release, it is believed to have been two Russian bomber planes and two fighter jets.
The planes are said to have penetrated 2.5 kilometres into Finnish territory. The incident occurred over the Gulf of Finland off the town of Loviisa, east of Helsinki.
"The investigation into the matter will continue over the coming weeks," writes the border guard.