A new report commissioned by the Finnish government is warning that possibility of the country joining NATO comes with serious risks, and that a membership bid could lead to a major “crisis” with neighboring Russia.

Russia has complained about NATO expansions along its border, and Finland shares a 1,340 km border with Russia. Finland was an autonomous part of Russia for much of the 19th century, and became independent in 1917. They clashed with the Soviets in the decades that followed.

Finland and neighboring Sweden are both neutral, but have been raised as potential NATO members in the future. Though the report found that Finland might see some security benefits from joining the alliance, it cautioned that it would also do major harm to trade with Russia.

Finland is massively dependent on exports economically, and Russia is their third largest customer. This potential damage to the economy would likely not be worth limited security benefits when Finland hasn’t had any major dust-ups with Russia in generations.

The report did say that a joint membership bid with Sweden might somewhat lessen the economic repercussions with Russia, and warned that joining without Sweden would leave therm an isolated NATO member with no common borders. Finnish officials say there is a promise between them and Sweden not to “surprise each other” on the matter.

Polls show overwhelming opposition among Finns to the idea of joining NATO at any rate, with the most recent poll by broadcaster YLE seeing 55 percent of the public opposed, and only 22 percent of voters in favor of the idea of joining.