Finnish President Sauli Niinisto and Prime Minister Sanna Marin said Thursday that their country must submit an application to join the NATO military alliance "without delay", a major policy shift triggered by the invasion. Ukrainian Russian.

Sweden's ruling Social Democrats are expected to decide on Sunday whether to reverse decades of opposition to NATO membership, a move that would almost certainly lead Sweden to apply to join the alliance.

The two countries had held for decades the belief that the best way to keep the peace was not to publicly choose sides.

This accession process is expected to be much shorter than previous applications to join the alliance founded in 1949. While there is no set time frame, here are the steps in the NATO membership process that would apply to Helsinki and Stockholm:

NATO officials and diplomats say that, ideally, the two countries should submit their requests together, most likely in the form of letters sent to NATO headquarters, to simplify the bureaucratic procedure.

Some diplomats hope that Finland and Sweden will apply for membership a few weeks before the Madrid summit in June to allow approval during the meeting, which will be attended by all allied leaders, including US President Joe Biden.

Representatives of the 30 allies meet in Brussels to discuss, and probably accept, the application for membership.

While many other hopefuls, such as Ukraine and Georgia, have been asked to carry out reforms before an application can be accepted, Finland and Sweden are considered successful democracies with militaries that meet NATO standards.

This step is also likely to take place in Brussels at NATO headquarters, taking just one day for each country, which must commit to complying with the terms of NATO's founding Washington Treaty. The two countries are already seen as "contributing to the security of the North Atlantic area," as required by the treaty.

Known informally as NATO's "wedding vows," officials in Helsinki and Stockholm would be asked whether they will uphold NATO's collective defense pledge that an attack on one ally is an attack on all.

They would also have to agree to pay their share of NATO budgets, participate in NATO defense planning and promise to abide by the rules on classified information.

The 30 allies are likely to grant membership to Finland and Sweden, granting them observer status at all allied meetings. However, they would not yet be covered by NATO's collective defense guarantee.

Diplomats and alliance officials have assured the Reuters agency that the candidacies would surely be approved, either on or before a planned summit in Madrid from June 28 to 30. "There is no exact timetable. We will not wait for the Madrid summit if it can be approved earlier," a NATO official said.

All allied parliaments must ratify a membership approval by the national governments. This can take anywhere from four months to a year, depending on elections, bureaucratic delays, and summer vacations. After the "deposition of ratification" of all allies, both Finland and Sweden must also deposit their "instrument of accession" with the US State Department, ultimately making both countries NATO allies .

Finland and Sweden have asked for guarantees that NATO countries will defend them while any application is processed and until they become full members. The secretary general of the alliance, Jens Stoltenberg, has assured that both countries will be able to unite "quickly" and that he was sure that arrangements could be found for the intermediate period. Sweden and Finland have received guarantees of support from the United States, Germany and Britain in case they are attacked.

Finnish Foreign Minister Pekka Haavisto acknowledged that submitting an application alone would not bring the two countries under the umbrella of Article 5, which guarantees that an attack on one ally is an attack on all. "But at the same time, NATO member countries have an interest that no security breaches occur during the application period," he said.

Moscow has repeatedly warned of "serious consequences" if Finland and Sweden join NATO, saying it would have to strengthen its ground, naval and air forces in the Baltic Sea, and has raised the possibility of deploying nuclear weapons in the area.

Russia and Finland share a 1,340 kilometer border. The Kola Peninsula, in Russia's northwestern Arctic pointing east from the border with Finland and Norway, is a "strategic stronghold" that Moscow sees as key to its national security, and is also home to Russia's Northern Fleet. Russia. Russia's second largest city, Saint Petersburg, is located about 170 kilometers from the Finnish border.