NATO Secretary General Jens Stoltenberg said it will be historic when the military alliance raises the Finnish flag for the first time at its headquarters on Tuesday, News.az reports citing CNN.

“This is a historic week. Tomorrow we will welcome Finland as the 31st member of NATO, making Finland safer and our alliance stronger. We will raise the Finnish flag for the first time here at NATO Headquarters,” Stoltenberg said, speaking in Brussels Monday.

“It will be a good day for Finland’s security, for Nordic security, and for NATO as a whole,” Stoltenberg added.

Finland is set to become a member of the alliance on Tuesday, with Finnish President Sauli Niinistö traveling to Brussels to attend an accession ceremony at NATO headquarters.

Stoltenberg also spoke about Sweden’s bid to join NATO, saying Finland’s accession is “in itself something we should celebrate” but is also good for Sweden. 

“It makes Sweden more integrated into NATO and makes Sweden even more safer,” Stoltenberg said, adding “at the same time we celebrate and enjoy that Finland is now full-fledged member, we should continue work to finalize the Swedish accession process.”