Donald Trump stood before the White House press room cameras on Thursday to perform a traditional presidential duty – consoler-in-chief during a time of tragedy.

He said the country was in mourning, shared his condolences during "an hour of anguish" and paid tribute to first responders and the victims.

Then he sharply pivoted - providing yet another reminder of how his new presidency is going to be very different.

It will be combative. It will be unscripted. And it will be quick to point the finger of blame.

"We do not know what led to this crash, but we have some very strong opinions and ideas," he said.

He then speculated that lowered standards of hiring for air traffic controllers in the Federal Aviation Administration during the Joe Biden and Barack Obama presidencies may have been a factor in the disaster.

Trump and his fellow Republicans have regularly attacked "diversity, equity and inclusion" programmes in the federal government.

His team has made undoing such programmes a core part of their first days in office, saying they have divided Americans and weakened the country.

And less than 24 hours after the first major US air disaster in more than a decade, Trump – along with his secretaries of transportation and defence, and his vice-president – took turns hammering their point, even as they provided no evidence that federal hiring practices had any connection to this particular crash.

Asked by a reporter how he could blame diversity programmes for the crash when the investigation had only just begun, the president responded: "Because I have common sense."

At other moments, he acknowledged there was no confirmed cause, saying "it's all under investigation".