ATLANTA — Jimmy Carter is celebrating his 95th birthday, becoming the first U.S. president to reach that milestone as he continues his humanitarian work and occasionally wades back into politics and policy debates almost four decades after leaving office.

Carter, who served from 1977-1981 and still lives in tiny Plains, Georgia, planned no public celebrations on Tuesday.

The 39th president, born in 1924 and raised during the Great Depression, has slowed physically in recent years, acknowledging recently that he has trouble walking after hip replacement surgery in May. But he remains active with programs at the post-presidency center he and Rosalynn Carter opened in Atlanta in 1982. He still teaches Sunday School at Maranatha Baptist Church in Plains. The Carters plan to travel later this week to Nashville, Tennessee, where they will help build houses for Habitat for Humanity.

Carter survived a dire cancer diagnosisin 2015 and became the longest-lived U.S. president in history this spring, surpassing George H.W. Bush, who died in 2018. Rosalynn Carter, now 92, is among the longest-lived first ladies. The couple has been married 73 years.

In recent public appearances, the former president has sounded like a man still intent on securing his legacy, amplifying his criticisms of American military spending and war, blasting the proliferation of money in U.S. politics and urging action to combat the climate crisis. And he's expressed particular pride that the U.S. engaged in no foreign wars during his tenure.

"I just want to keep the whole world at peace," Carter said in September during his annual Carter Center report.

"We have been at war more than 226 years. We have been at peace for about 16 years," he said of the U.S. since the Declaration of Independence in 1776. He asserted that every U.S. military conflict from the Korean War onward has been a war of "choice."

"The United States is very deeply inclined to go to war," Carter said, partly as "a mechanism by which we can implant American policies ... in other countries." A Naval Academy graduate and World War II veteran, Carter said presidents feed the cycle, in part because "we make a hero" out of wartime commanders-in-chief.

The Carter Center, which has focused mainly on public health, election monitoring and conflict resolution, has "never voiced an opinion publicly" on individual wars, Carter noted.

"This is primarily my fault," the former president said, explaining that he wants the center to become a more forceful advocate on questions of war around the world, including "wars by the United States." He said the Carter Center could engage in "constructive criticism of the United States government ... without being partisan about it."

An outspoken Christian, Carter sometimes frames his views on war in terms of his faith, noting that Jesus is referred to in the Bible as the "prince of peace." But at the Carter Center in September and a day later in his town hall with Emory University freshmen, the former president emphasized economic consequences of war.