In rare public remarks, Gen Dempsey spoke out against Mr Trump

Another senior former military officer has denounced President Donald Trump's threat this week to use troops to suppress violent protests in the US.

The ex-Joint Chiefs of Staff Chairman, Gen Martin Dempsey, told National Public Radio that Mr Trump's remarks were "very troubling" and "dangerous".

Mr Trump's current and former defence secretaries have also spoken out.

Mainly peaceful protests have spread across the US since the alleged police murder of an unarmed black man.

While demonstrations over George Floyd's death in Minneapolis, Minnesota, last month appear to be simmering down in the nation's capital, the White House's security perimeter has kept expanding in recent days.

"The idea that the president would take charge of the situation using the military was troubling to me," said Gen Dempsey in rare public remarks on Thursday.

"The idea that the military would be called in to dominate and to suppress what, for the most part, were peaceful protests - admittedly, where some had opportunistically turned them violent - and that the military would somehow come in and calm that situation was very dangerous to me," he added.

Gen Dempsey served as America's most senior military officer under former US President Barack Obama from 2011-15.

His criticism comes a day after former Marine Gen Jim Mattis, Mr Trump's former Pentagon chief, denounced the president, saying he deliberately stokes division.

"Donald Trump is the first president in my lifetime who does not try to unite the American people - does not even pretend to try," Mr Mattis wrote in the Atlantic magazine. "Instead, he tries to divide us."

Mr Trump hit back via Twitter at the "overrated general".

Earlier that day, Mr Trump's current Defence Secretary Mark Esper had also spoken up.

He said the use of active-duty forces to quash unrest across the nation would be unnecessary at this stage, in remarks that are known to have displeased the White House.

Mr Trump said on Monday from the White House Rose Garden that he would act to disperse violent protesters.

"If a city or a state refuses to take the actions that are necessary to defend the life and property of their residents," he said, "then I will deploy the United States military and quickly solve the problem for them."

While he spoke, authorities used force to disperse a mainly peaceful protest nearby so the president could walk to a historic church that was damaged by fire in the unrest and be photographed holding up a Bible.

The justice department had ordered Lafayette Square, just outside the executive mansion, to be fenced off for Mr Trump's walkabout.

By Thursday afternoon, that security zone was significantly expanded, with high fencing installed around the park area known as the Ellipse just south of the White House.

Also on Thursday, a moderate Republican Senator Lisa Murkowski broke ranks to say she was unsure if she would support Mr Trump's bid for re-election.

In what is being seen as the most outspoken criticism yet of the president from a senator in his own party, Ms Murkowski told the Washington Post: "I thought Gen Mattis' words were true and honest and necessary and overdue."

Shortly afterwards Mr Trump tweeted that he would campaign to throw the Alaska senator out of office when she is up for re-election in 2022. BBC