The North Atlantic Treaty Organization (NATO) will hold a summit this weekend in Warsaw, Poland. Among the topics that will be discussed, one of the most important is European defense spending.

NATO members have committed to spending at least 2 percent of gross domestic product (GDP) on defense. European member states, however, currently spend an average of 1.4 percent of GDP.[1]  Overall, annual European defense spending totals $227 billion, which breaks down to an average of $1.09 per person per day. If Europeans spent just 48 cents more per person per day, defense spending across the continent would reach the 2 percent goal. Doing so would contribute over $100 billion additional funds to security spending in Europe each year.

For its part, Canada spends $16 billion annually on defense, which is only 1 percent of its GDP. Canada would need to double its defense budget to reach that goal. While Canada spends more than Europe per capita each day on defense ($1.22), doubling its defense budget would only mean spending an additional 1 cent per person per day.

The United States spends more on security than other NATO members, given its global leadership, interests, and alliances. The annual U.S. defense budget is $650 billion, which is 3.6 percent of its GDP. That equals $5.54 per person per day.

With threats ranging from domestic terrorism and Russian aggression to cyberattacks and the refugee crisis, the transatlantic alliance is indispensable to American national security. NATO is essential for European peace and stability as well, and our allies across the Atlantic should demonstrate their commitment to collective security by working to increase domestic defense spending. There can be little doubt that it would be worth the additional 50 cents per person a day.

[1] Four European NATO members—Estonia, Greece, Poland, and the UK—do spend 2 percent or more on defense.