MADRID — President Joe Biden on Wednesday pledged to boost American military operations in Europe as he seeks to project a picture of strength and unity among NATO members while they grapple with Russia's invasion of Ukraine.

The announcement comes as NATO leaders begin the first full day of meeting in Madrid in what could be one of the most consequential gathering in the military alliance's 73-year history.

"In a moment when Putin has shattered peace in Europe and attacked the very, very tenants of rule based order," Biden said.

The agreement to expand NATO, along with announcements about increasing the number of troops in the east, is intended to greatly bolster the alliance's abilities to fend off any potential Russian aggression toward its member states.

The last time the NATO leaders met, for an emergency meeting in Brussels in March, there was a sense of triumph among the members as they locked arms against Russia, fearing they could be next if Ukraine were to fall.

But while the 30 NATO members have maintained their resolve in supporting Ukraine, there have been diverging views over the intervening months on a variety of issues, from how far to go in punishing Russia to the level of military preparedness needed.

Before the start of the meeting, NATO Secretary General Jens Stoltenberg announced a major overhaul of the group’s military posture and priorities, increasing the number of its forces at high readiness to more than 300,000 from the current level of 40,000, along with bolstering military supplies and equipment in the NATO members bordering Russia. .

But a number of questions remain this week, such as how to fund efforts to build up NATO’s defenses

Just nine of the member countries are meeting the NATO target of spending 2 percent of their gross domestic products on defense, an amount that Stoltenberg said is becoming the “floor and not the ceiling.”

“We do think that there is increasing convergence, both at the G-7 and at NATO, around the challenge China poses,” Sullivan said