Russia on Thursday announced tightened security in its northern Murmansk region after Finland said it would close all but one border crossing between the two countries.Helsinki said Wednesday the move follows a surge in attempted crossings by migrants seeking asylum in the EU country — which Finland says is a destabilization ploy by Russia."A decision has been taken to introduce a heightened state of readiness in the Murmansk region, and a number of additional measures to ensure the security of our residents," Murmansk governor Andrey Chibis said in a social media post.He did not provide details.Relations between the two countries, which share a 1,340-kilometer border, have soured after Moscow launched its military offensive on Ukraine and Finland joined the NATO military alliance.Chibis said Finland's decision to only keep its northernmost border crossing open would result in a "significant increase" in the number of migrants seeking to cross into Finland from his Arctic region.Around 400 people were waiting to cross through the Salla border on Wednesday, he said — 50 of whom were allowed to enter Finland.Helsinki has accused Moscow of allowing migrants without documents to cross their common border.It has seen an influx of attempted border crossings by people from the Middle East and Africa since late August.