Finland flag
© Nigel Marple / Reuters
The prospect of Finland joining NATO would lead to a crisis in relations with neighboring Russia, government report states. With Sweden being a non-NATO member, Finland would be "isolated and exposed" if it joins the military bloc, it adds.

"Political and economic reactions may be strong, even harsh, notably during the transition phase. Even while stopping short of the use of force, specific counter-measures would be difficult to predict," a report prepared for Finnish Prime Minister Juha Sipila's government states.

It also predicts that the country's membership in the military alliance which repeatedly called Russia an 'aggressor' and severed political ties with it following Crimea's accession would severely affect trade between the two countries.

"This is a question of grand strategy," Finnish Prime Minister Sipila said commenting on the predictions.

Finland shares a 1,340 km-long border and a long history full of controversies with Russia, which it used to be part of. The 60-page report stresses that joint Finnish-Swedish application is a better strategic alternative than a separate move towards NATO membership by either of these two countries.

"Mutual cooperation between the Nordic neighbors when decisions are made about joining NATO [are crucial]," it states, stressing that it would be "considerably more benign for Finland" if the two countries joined at the same.

The report explains that if Finland joins NATO the latter's border length with Russia would be doubled, however, without Sweden, Finland would be left as an isolated enclave, difficult to defend.

"Similarly, a Swedish decision to join NATO and a Finnish decision not to join would leave Finland isolated and exposed." Sipila said that the governments of Finland and Sweden had already promised not to "surprise each other" on joining NATO if it comes to it.

Sweden's government recently said it did not intend to join the alliance, but four opposition parties want membership, with polls in the country showing that the population is also split on the matter. In Finland, however, a majority opposes the prospect. According to a recent poll by Finnish public broadcaster YLE only 22 percent of Finns support joining NATO, while some 55 percent are against it.

Earlier on Friday, commenting on the prospect of Sweden joining NATO, Russian Foreign Minister Sergey Lavrov said that while Russia is not interested in neutral Sweden entering the alliance, "any state has the right to decide independently on the forms of ensuring security" and "if Sweden decides to join NATO, we won't think that it intends to attack us."

However, he also pointed out that alliance infrastructure in Sweden would definitely spark a reaction from the Russian military.

"It's one thing to have neutral neighbors in the North and another to have neighbors who are members of the North Atlantic alliance," Lavrov told Swedish newspaper Dagens Nyheter in an interview published Friday.

"[If Sweden decides to join NATO] we will have to take the necessary defense measures on our Northern borders, based on the fact that there is a military political bloc across the border, which regards Russia a threat and intends to deter it."

Meanwhile, German media citing a Defense Ministry spokesman reported on Friday that NATO is looking at strategies to further boost its presence in Eastern Europe, including sending German troops to Lithuania.

"There are various models under preliminary discussions and voting in NATO is underway," the ministry's spokesman Jens Flosdorff told the DPA news agency. "Decisions will be made this fall at the NATO summit in Warsaw."

The military alliance is to meet in the Polish capital of Warsaw in July. The 28 member states are expected to agree on a roadmap to enhance combat readiness in Eastern Europe and the Black Sea, which it's been bolstering since the Ukrainian crisis began in 2014.