Jimmy Carter celebrated his 95th birthday on Tuesday, becoming the first U.S. president to reach that milestone as he continues his humanitarian work and occasionally weighs in on politics and policy.

Carter still lives in tiny Plains, Georgia, and planned no public celebrations on Tuesday. But he’s had plenty to say recently, warning that re-electing President Donald Trump would be “a disaster” and expressing hopes that his Carter Center will become a more forceful advocate against armed conflicts in the future, including “wars by the United States.”

“I just want to keep the whole world at peace,” Carter said as he presented his annual Carter Center report last month.

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

The 39th president survived a dire cancer diagnosis in 2015 and surpassed George H.W. Bush as the longest-lived U.S. president in history this spring. He’s had some trouble walking after a hip replacement in May, but still teaches Sunday School in Plains, and with his wife of 73 years, Rosalynn, now 92, still plans an upcoming trip to help build houses with Habitat for Humanity in Nashville, Tennessee.

In his latest appearances at the Carter Center and in a town hall at Emory University, Carter blasted money in politics, urged action to combat the climate crisis, and celebrated the Carter Center’s work on public health, election monitoring and conflict resolution. But he said the center can do more to constructively criticize U.S. military engagements. The Carter Center has “never voiced an opinion publicly” on individual wars, he said with some regret, adding: “This is primarily my fault.”

“The United States is very deeply inclined to go to war,” Carter said, partly to “implant American policies” in other countries, and partly to “make a hero” out of wartime commanders in chief. This has significant economic consequences, he said: China has “been at peace” since he normalized relations with Beijing in 1979, and while the U.S. has spent trillions on military conflict, China has invested similar amounts in high-speed rail, new college campuses and other infrastructure.

Carter talks with the realism of a nonagenarian, born in 1924 when the world population was quarter of what it is today and life expectancy for American males was 58 years. Saying he plans to start spending more time with his extended family, he told the Carter Center audience that “this may be our last conversation with you … we may or may not have one next year.”

Carter has been accepting visits from several 2020 presidential candidate s, but he’s held back on endorsing any of his fellow Democrats, offering only clues to his thinking.

Carter said he voted for Bernie Sanders over Hillary Clinton last time, but warns that embracing single-payer, government-run health insurance could cost the Democrats votes among moderates and independents. That could rule out Sanders and another progressive favorite, Elizabeth Warren. But Carter also said he’d like to see a woman as president. He said he couldn’t have managed his presidential duties when he was 80, which would nix not only Sanders, at 78, but former Vice President Joe Biden, who is 76. Warren is 70, meaning she’d be nearly 80 at the end of a two-term presidency.

Carter said only that he’ll be “voting Democratic” in the general election. By then, he’ll be 96.