U.S. Secretary of State Rex Tillerson called for a return to civilian rule in Zimbabwe, saying the southern African country must hold free and fair elections in the wake of signs that longtime authoritarian leader Robert Mugabe will be forced from power.

“We should work together for a quick return to civilian rule in that country in accordance with their constitution,” Tillerson said Friday at a gathering of African foreign ministers and diplomats at the State Department.

He continued: “Zimbabwe has an opportunity to set itself on a new path: one that must include democratic elections and respect for human rights. Ultimately the people of Zimbabwe must choose their government.”

President Robert Mugabe made his first appearance on Friday after the military put him under house arrest. (AP)

Tillerson’s comments come as Mugabe made a public appearance at a university graduation – his first public outing since the military put him under house arrest earlier this week.

ZIMBABWE'S MUGABE MAKES 1ST PUBLIC APPEARANCE SINCE MILITARY TAKEOVER

The U.S. Embassy in Harare said in a statement Thursday the U.S. government is “deeply concerned” by the actions taken by the Zimbabwean military.

“We call on the Zimbabwean military leaders to exercise restraint, respect the rule of law, uphold the constitutionally-protected rights of all citizens, and to quickly return the country to normalcy,” the statement said.

The military has announced "significant progress" in talks regarding Mugabe's departure and has arrested some of his allies. Branches of Mugabe's ruling party, meanwhile, began to pass no-confidence votes in the world's oldest head of state who has been in office for 37 years.

Despite his arrest, Zimbabwe's military has taken pains to show respect for the 93-year-old leader by referring to him in public statements as the president and the commander in chief.

WHO IS GRACE MUGABE, AFRICA'S MOST POLARIZING FIRST LADY?

Grace Mugabe has positioned herself to be the only successor to her husband, Zimbabwean President Robert Mugabe. (AP)

There was no sign of first lady, Grace Mugabe, at Friday's graduation ceremony, which allowed Mugabe to project the image of leadership. Some Zimbabweans worried Mugabe, the only leader many have ever known, would somehow find a way to stay on.

The Trump administration has taken a largely hands-off approach to Zimbabwe in contrast to the three previous U.S. administrations of Presidents Bill Clinton, George W. Bush and Barack Obama.

All three actively sought to isolate Mugabe and his ruling clique due to increasing human rights abuses, hoping to encourage a democratic transition. Since Trump moved into the White House in January, however, Washington has been virtually silent on the matter.

Tillerson's comments on Friday appear to be only the second time he has mentioned the country in a public setting. The first was a three-sentence written statement released by the State Department on the anniversary of Zimbabwe's independence day in April.

ZIMBABWE CRISIS: WHO ARE THE KEY PLAYERS?

All five of his immediate predecessors as secretary of state — Madeleine Albright, Colin Powell, Condoleeza Rice, Hillary Clinton and John Kerry — delivered speeches in which they had denounced Mugabe's consolidation of power through violent suppression of dissident voices, other rights abuses and the controversial seizures of white-owned land.

U.N. envoy Nikki Haley mentioned Zimbabwe and Mugabe in a June speech but her critique was focused on excoriating the U.N. Human Rights Council for failing to address despotic regimes in general.

The Associated Press contributed to this report.