Nato is set to significantly increase in size and strength after Turkey dropped its veto to Finland and Sweden joining the alliance late on Tuesday.
After two hours of talks with the leaders of the Nordic countries, President Recep Tayyip Erdogan agreed to allow the applications to go ahead, meaning the countries will be fast-tracked into the 30-nation alliance.
Both countries bring formidable military power and Finland’s 1,300-kilometre border with Russia means that Moscow will have a border with Nato stretching from the Arctic to the Mediterranean Sea.
“I am pleased to announce that we now have an agreement that paves the way for Finland and Sweden to join Nato,” Nato Secretary General Jens Stoltenberg said during a press conference.
“Turkey, Finland and Sweden have signed a memorandum that addresses Turkey's concerns, including around arms exports, the fight against terrorism and extradition.”
Mr Stoltenberg said the admission of the two countries would chart a blueprint for the alliance “in a more dangerous and unpredictable world”, changing regional security and strengthening Nato's presence in Europe.
“The two members will bring to Nato advanced and well developed forces, advanced weapons system technology and stable political institutions, they will strengthen Nato and Finland and Sweden,” Mr Stoltenberg said.
The countries' three foreign ministers signed a trilateral memorandum on Tuesday confirming that Turkey would support the bids of Finland and Sweden to become Nato members.
“The concrete steps of our accession to Nato will be agreed by the Nato allies during the next two days, but that decision is now imminent,” said Finnish President Sauli Niinisto in a statement.
Turkey’s objection to Finland and Sweden's membership had threatened to overshadow the summit that is seeking unity as Russia wages war in Ukraine.
Ankara’s main concern had been over Finland and Sweden’s tolerance of the PKK, a Kurdish nationalist organisation widely described as a terror group.
It now appears that both Nordic countries have given reassurances and guarantees to address the PKK issue.
“Over the past weeks, Turkey has raised its concerns over the threat of terrorism,” Mr Niinisto said. “Finland has constantly taken these concerns seriously. Finland condemns terrorism in all its forms and manifestations. As a Nato member, Finland will commit fully to the counterterrorism documents and policies of Nato.”
He added that his country now looked forward to “fruitful conversations on Finland’s role in Nato with our future allies here in Madrid”.
The Finnish military is regarded as well trained and is able to call up to 240,000 soldiers on to a war-footing in a short period. Its navy in the Baltic Sea is also being reinforced with new frigates and it has signed a deal to buy 64 US F-35 stealth fighter jets. Turkey is understood to be in discussions with US President Joe Biden over the purchase of 40 F-16 fighters.
In joining Nato, Finland and Sweden join fellow Nordic countries Norway and Denmark.
"I congratulate Turkey, Finland and Sweden on signing a trilateral memorandum, which paves the way for allies to invite Finland and Sweden to join Nato at the Madrid summit," US President Joe Biden said in a statement.