If Putin Crosses the Line, These Are the Armies He’ll Have to Deal With

Key Points

Putin’s expansionist ideology and aggressive military behavior has NATO countries worried about encroachment.
NATO countries are also concerned about how the U.S. might react, so European NATO members are building up defense capabilities.
The NATO member with the most military power has over 391,000 military vehicles.
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By Jenn Boozer Published Apr 18, 2025 at 9:30 AM EDT

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If Putin Crosses the Line, These Are the Armies He’ll Have to Deal With — © Glen Richard / iStock via Getty Images

What would happen if Putin escalated Russia’s ongoing conflict with Ukraine and attacks a NATO member country? Given current events, the answer is far from straightforward. The NATO alliance is currently facing internal tensions due to disagreements between the United States and European allies over handling the war between Ukraine and Russia. Recent actions by former U.S. President Donald Trump, including a softer stance toward Russian President Vladimir Putin, have made European countries uneasy. Trump’s apparent willingness to break from his NATO allies directly contrasts the beliefs of the American people — 66% of whom say that America benefits from its membership in the alliance, and 72% of whom believe that Russia is an enemy to our nation. Allies worry about America’s commitment to NATO’s core mission of collective defense against Russia, causing some European countries to consider strengthening their own defense capabilities independently. This comes at a challenging time, especially as Russia and Belarus are believed to be preparing to preemptively strike against certain NATO members. (What would the world today look like without NATO?)

In response, European nations are looking at new plans to protect Ukraine without relying solely on NATO. For example, the UK and other countries considered sending fighter jets to defend Ukrainian skies or sending troops to help — though the latter plan is supposedly being walked back on. France’s President Emmanuel Macron has also suggested using the French nuclear program as a possible shield for Europe, signaling a move toward greater independence from U.S. protection. These differences highlight growing cracks within NATO, creating uncertainty about the alliance’s future unity. To determine the NATO members with the strongest military might, 24/7 Wall St. reviewed the 2025 Military Strength Ranking from Global Firepower, an annually updated defense-related statistics website with information on 145 countries. Global Firepower ranked 145 countries based on their PowerIndex, a composite of over 60 measures in categories such as military might, financials, logistical capability, and geography. The smaller the PowerIndex value, the more powerful a nation’s theoretical conventional fighting capability is. The countries on our list are listed in ascending order from least powerful to most powerful military. We included supplemental information regarding active military personnel, military aircraft, vehicles, and naval power as well, also sourced from Global Firepower.

This article was updated in April 2025 to provide new Global Firepower data, as well as to provide an overview of recent conflicts associated with NATO members.

Why Is This Important?

NATO members work together to tackle crisis management, promote democracy, and create peaceful resolutions to disputes. Its principle of collective defense in Article 5 is the group’s hallmark and speaks to the cooperation encouraged between countries. But could this principle, only invoked once after the terrorist attacks in the United States on 9/11, need to be invoked again soon?

While it’s unlikely at this point that NATO will use Article 5 as any justification, increasing tensions could highlight why collective defens may become a strategy in the coming years. Russia’s Foreign Intelligence Service (SVR) Director Sergey Naryshkin has even said that any “NATO aggression” against Russia would lead to Russian force against Poland, Lithuania, Estonia, and Latvia. This comes soon after the Baltic nations withdrew from the Ottowa Convention out of fears of diminished regional security. Though next steps are unclear, it seems as though some nations are beginning to prepare for a potentially inevitable global conflict if Russia continues pushing its territorial goals in Ukraine and beyond. (These NATO countries are ramping up defense spending.)

Here are the NATO countries with the strongest militaries.