NATO allies have been expecting Finland and Sweden to apply to join the military alliance in the coming days, and will grant membership quickly, according to diplomats and officials.

During the one-year ratification of their membership, NATO allies will be ramping up troop presence in the Nordic region, in addition to holding military exercises and naval patrols in the Baltic Sea and possibly rotating US and British forces in Finland and Sweden, according to the sources.

The two countries, however, will not be benefitting from NATO's collective defense clause; the clause entails that an attack on one ally is an attack on all allies. Finland and Sweden will be benefiting from the clause if the 30 member states support the decision. 

Norway, Denmark, and three Baltic states in the wider Nordic region are already NATO members.

The president of Finland, Sauli Niinisto, will be announcing his stance on the matter on Thursday, which will pose as an official confirmation of Finland's decision.

Read more: Finland joining NATO 'would not be against anyone': President

Sweden, on the other hand, will be deciding on Sunday whether it will be flipping the tables on their previous, long-standing opinion NATO membership opposition. 

Stockholm is holding an all-party review of security policy which will be reported on Friday.

"Yes and yes: they will apply and they will be granted membership," said one senior diplomat, who asked to remain anonymous.

Kremlin spokesman Dmitry Peskov declined on Wednesday to comment on Russia's possible reaction.

"Of course, we observe everything that is connected with actions that are capable of somehow changing the configuration of the alliance near our borders in the most attentive way," he said. "This is a subject for very, very careful analysis. For now, we can't say any more."

Sweden Social Democrats divided on joining NATO

Last week, ahead of a critical month for Sweden and Finland, the Swedish Social Democrats' divide over the country's possible application to join the NATO alliance became clear as it threatened to end nearly 200 years of neutrality.

By Friday, May 13, Sweden will publish a security policy assessment report that will involve representatives of all parties in the Swedish parliament - the Riksdag.

Before the government takes a decision on submitting an application to join the NATO, the Swedish foreign ministry is due to publish a position paper by May 24.

Swedish media cited Climate and Environment Minister, Annika Strandhäll, who also serves as a federal board chair of the women’s wing of the Social Democrats - as saying that the women's wing had “a long history and struggle in matters concerning peace, disarmament, detente and military freedom of alliance."

“[We] in the federal board have decided to remain in line with our congressional decisions that Sweden should be militarily non-aligned and stand outside NATO,” confirmed Strandhäll.

Two-thirds of Finnish ministers in favor of joining NATO

For his part, Finnish President Sauli Niinistö said he will make his views on the NATO matter public by 12 May, after Russian President Vladimir Putin gives his speech on May 9, on the occasion of Russia’s Victory Day. Later this month, Niinistö is scheduled to make a two-day visit to Sweden.

It is noteworthy that Moscow has denied reports claiming that the Russian President will announce a war on Europe on May 9. However, it warned of unspecified consequences if Sweden and Finland join NATO.

In regard to Finland, which shares an 830-mile border with Russia, a survey of the parliament revealed that around two-thirds of Finnish ministers are in favor of joining NATO.

The ruling Finnish Social Democrats will hold a debate on the matter on 14 May.