dpaBrussels Sweden and Finland took an important step towards NATO membership on Tuesday, when the 30 allies signed accession protocols to invite both Nordic countries to join the alliance."This is truly a historic moment. For Finland, for Sweden, for NATO, and for our shared security,” NATO Secretary General Jens Stoltenberg said at the signing ceremony."The membership of both Finland and Sweden will not only contribute to our security, but to the collective security of the alliance,” Finnish Foreign Minister Pekka Haavisto said."We are tremendously grateful for all the strong support that our accession has received,” added Swedish Foreign Minister Ann Linde.Once ratified, the accession protocols will allow Stoltenberg to formally invite both Nordic countries to join NATO.However, it could take another six to eight months for all 30 NATO members to complete the ratification process. The procedure differs from country to country but usually requires parliamentary approval.During this interim period, there are concerns about Sweden and Finland’s exposure to Russian aggression. The United States and Poland, among others, have pledged support in the event of an attack, while British Prime Minister Boris Johnson has signed security pacts with both countries.From now on, Sweden and Finland can attend all meetings of the alliance members’ ambassadors.Both countries have cooperated closely with NATO for years in security exercises. However, they had attempted for years to balance relations with Russia.Finland shares a long border with Russia and the two Nordic countries have a tense history of wars and occupation with their large eastern neighbour.Shaken by the Russian invasion of Ukraine, Sweden and Finland applied to join NATO on May 18.For weeks, Turkey blocked progress over concerns linked to terrorism.