A new survey shows that less than half of Americans support the North Atlantic Treaty Organization, an alliance originally designed to provide collective security against the Soviet Union, but now focused on Russia and non-state actors such as the Taliban and the Islamic State group.

The YouGov survey, released to commemorate the 70th anniversary of NATO, found that only 44 percent of Americans support the United States’ place in the agreement. That was down 3 percentage points from when the survey was conducted in 2017.

The poll also surveyed other NATO countries and found that support for the alliance had decreased significantly in the past two years among key European allies. Support for NATO dropped in Britain from 73 percent to 59 percent, in Germany from 68 percent to 54 percent, and in France from 54 percent to 39 percent.

YouGov said there is a generational divide in the United States over support for NATO, with 56 percent of the Baby Boomer generation, who grew up at the beginning of the Cold War, believing that the treaty continues to serve an important role in defending Western nations. Only 35 percent of Millennials and 33 percent of Generation X members support U.S. participation in the alliance.

There is also a political divide, according to the survey, with 60 percent of Democrats in the United States agreeing the alliance serves an important role, while only 38 percent of Republicans believe the same.

YouGov contacted more than 1,200 U.S. adults for the survey, which was conducted online, as well as more than 1,000 adults in several European countries.

NATO was formed to be an alliance of Western nations that would balance the military power of the Soviet Union and its allies in Eastern Europe. After the former Soviet Union collapsed in 1991, some experts questioned what part the alliance would play in international security, but the return of Russian assertiveness under President Vladimir Putin has partly changed that.

NATO has expanded to include countries that were once part of the Soviet bloc, and has also added countries that are further away, such as Turkey and Greece.

U.S. President Donald Trump has repeatedly criticized the group, saying many NATO members do not spend enough on defense to fully meet their commitments under the agreement.