Finland’s President Sauli Niinisto and Prime Minister Sanna Marin said Thursday that the country should apply to join NATO “without delay.”

Thursday’s announcement is the strongest sign yet that Finland will make a formal application to join NATO. Membership would be historic for the Nordic country, which has had a decades-long policy of military neutrality.

“Finland must apply for NATO membership without delay.” the leaders said in a joint statement, adding that they hoped that “the national steps still needed to make this decision will be taken rapidly within the next few days.”

“NATO membership would strengthen Finland’s security” and that Finland’s membership would in turn “strengthen the entire defence alliance.”