I'm not an expert but NATO is very small compared to Russia. Russia is usually the aggressor as well which means NATO's defense systems would have to repel something that they may not see coming.
International Level: Junior Politician / Political Participation: 71 7.1%
'The US is prepared to defend every inch of NATO territory,' Vice President Kamala Harris says. Vice President Kamala Harris recommitted the United States support to defend NATO territories after meeting with Poland’s president Thursday morning. "The US' commitment to Article V is ironclad,” Harris said during a press conference after meeting with Poland President Andrzej Duda. "The US is prepared to defend every inch of NATO territory." Source 9n.
Senate approves Finland and Sweden’s bid to join NATO, a key step in expanding the alliance amid Russia’s war in Ukraine. The resolution now goes to President Biden for his signature. All of NATO’s 30 member countries must ratify Finland and Sweden’s accession to the alliance. Source 4n.