Three US citizens were among 37 defendants sentenced to death by a military court on Friday for their involvement in a failed coup attempt in the Democratic Republic of Congo (DRC) in May.

On May 19, armed men briefly seized control of a presidential office in Kinshasa before security forces killed their leader, US-based Congolese politician Christian Malanga.

Among the Americans on trial were Malanga’s son, Marcel Malanga, and his friend, Tyler Thompson. Thompson had accompanied Marcel to the DRC. The third American, Benjamin Zalman-Polun, was a business associate of Christian Malanga.

All three were convicted of criminal conspiracy, terrorism, and other related charges, with the military court issuing death sentences during a ruling broadcast live on national television.

The proceedings revealed little about the motivations behind the events of May 19, with the defendants placing the blame squarely on Christian Malanga.

Tyler Thompson testified that they had been "forced" into participating. "I was forced to carry an arm," Thompson told the court. "I came to the DRC to visit Marcel's family who I had never seen before before," he added.

Marcel Malanga testified that his father had threatened to "kill us if we didn’t listen." He added that it was his first visit to the DRC after being invited by his father, whom he had not seen for years, while Benjamin Zalman-Polun claimed he had been "kidnapped" and "forced" to participate.

The Americans were part of a group of approximately 50 individuals, including citizens of the US, UK, Canada, Belgium, and the DRC, who were on trial following the coup attempt.

The sentencing took place at Ndolo military prison on the outskirts of Kinshasa, where the defendants, clad in blue and yellow prison uniforms, sat before the judge as the verdict was announced under a tent.

In Washington, State Department spokesperson Matthew Miller confirmed that US embassy staff attended the proceedings and would continue monitoring the case closely.

"We understand that the legal process in the DRC allows for defendants to appeal the court's decision," Miller said during a briefing.

The court acquitted 14 defendants, citing the investigation's conclusion that they had "no connection" to the events.

Last month, military prosecutor Lieutenant Colonel Innocent Radjabu recommended the death penalty for all but one defendant, who, according to a medical report, suffers from "psychological disorders".