WASHINGTON, United States (AFP) — United States (US) President Donald Trump said Tuesday that the United States would react strongly if authorities in Iran started hanging people in their crackdown on a popular uprising against the government.

“We will take very strong action if they do such a thing,” he told CBS News in an interview, when asked about hangings potentially beginning on Wednesday.

“When they start killing thousands of people — and now you’re telling me about hanging. We’ll see how that’s going to work out for them,” Trump said in a video clip released online.

The interview took place as Trump was in the northern US state of Michigan to visit a manufacturing plant and deliver a speech on the economy.

In his speech, Trump reiterated a message he had posted earlier on social media, that “help is on its way” for the Iranian protesters.

He also said it was unclear what the death toll in Iran actually was.

“I hear numbers — look, one death is too much — but I hear much lower numbers, and then I hear much higher numbers,” he said.

Later, speaking to reporters on his return to Washington, Trump said he would soon be receiving a briefing on Iran.

“The killing looks like it’s significant, but we don’t know yet for certain. I’ll know within 20 minutes — and we’ll act accordingly,” he said.

Trump had previously vowed the United States would get involved if protesters were killed, a line crossed days ago.

At least 734 people are confirmed to have been killed, though the actual death toll is likely in the thousands, Norway-based NGO Iran Human Rights (IHR) said Tuesday.

Fears have also grown that the Islamic Republic could use the death penalty to crack down on the protests, after Tehran prosecutors said authorities would press capital charges of “moharebeh,” or “waging war against God,” against some suspects arrested over recent demonstrations.

“Concerns are mounting that authorities will once again resort to swift trials and arbitrary executions to crush and deter dissent,” Amnesty International said.

IHR highlighted the case of Erfan Soltani, 26, who was arrested last week in the Tehran satellite city of Karaj and who, according to a family source, has already been sentenced to death and is due to be executed as early as Wednesday.