President Donald Trump expressed his "warmest sympathy" to New Zealand after a mass shooting at two mosques.

Unlike New Zealand's prime minister and other world leaders, Trump did not describe the incident as an act of terrorism, nor did he make any references to hatred or bigotry.

The president has often faced criticism for his response to incidents of violence and tragedy, particularly when bigotry is involved.

At least 49 people were killed in two New Zealand mosques on Friday in a mass shooting that world leaders quickly began decrying as terrorism and a vicious act of "racist hatred."

President Donald Trump, who was praised in the writings of the man who's claimed responsibility for the shooting, has not described the Christchurch mosque massacre in such terms. The suspect seemed to have a white nationalist philosophy, harboring vehement anti-Muslim and anti-immigrant sentiments. Experts in the field of 8chan message-board culture — where the suspect was a frequent poster — cautioned, however, that the apparent manifesto contained many ironic and misleading signals designed to amplify and sow chaos in coverage of the massacre.

Reacting to the shooting later than other global leaders, Trump on Friday morning tweeted: "My warmest sympathy and best wishes goes out to the people of New Zealand after the horrible massacre in the Mosques. 49 innocent people have so senselessly died, with so many more seriously injured. The U.S. stands by New Zealand for anything we can do. God bless all!"

The president did not mention terrorism, bigotry, or the suspect.

A subsequent tweet from the president on Friday afternoon regarding a phone call with New Zealand Prime Minister Jacinda Ardern also made no mention of terrorism and did not condemn hatred or bigotry.

"Just spoke with Jacinda Ardern, the Prime Minister of New Zealand, regarding the horrific events that have taken place over the past 24 hours, " Trump said. "I informed the Prime Minister that we stand in solidarity with New Zealand — and that any assistance the U.S.A. can give, we stand by ready to help. We love you New Zealand!"

The White House press secretary, Sarah Huckabee Sanders, issued a statement calling the incident an "act of hate," going further than her boss, but did not mention terrorism.

The US national security adviser, John Bolton, was also more direct than Trump in his language about the shooting in a conversation with reporters on Friday morning, saying: "We're obviously greatly disturbed on what seems to be a terror attack, this hate crime in New Zealand. We've been in touch with our embassy overnight, we're still getting details, but the State Department and others are following up on it."

Asked for comment from INSIDER, the White House did not directly address why Trump had not referred to the shooting as terrorism.

Read more: All of the extremist killings in the US in 2018 had links to right-wing extremism, according to new report

New Zealand's prime minister said the incident was a "terrorist act."

"What has happened in Christchurch is an extraordinary act of unprecedented violence," Ardern added on Twitter. "It has no place in New Zealand. Many of those affected will be members of our migrant communities — New Zealand is their home — they are us. The person who has committed this violent act has no place here."

British Prime Minister Theresa May referred to the shooting as a "horrifying terrorist attack."

German Chancellor Angela Merkel expressed solidarity with "citizens who were attacked and murdered out of racist hatred," adding, "we stand together against such acts of terrorism."

Similarly, French President Emmanuel Macron in a tweet said, "France stands against all forms of extremism and acts with its partners against terrorism in the world."

Trump has reacted to other acts of violence in far more explicit terms when less evidence was available. As the London police were still investigating an incident involving a car crash outside Parliament in August, for example, Trump tweeted, "Another terrorist attack in London...These animals are crazy and must be dealt with through toughness and strength!"

Read more: Right-wing violence has 'accelerated' in the US since Trump took office

In 2017, May criticized Trump over tweets he sent about a bomb on a London Underground train. Trump had tweeted that those responsible were "loser terrorists" and "sick and demented people who were in the sights of Scotland Yard." Local authorities were still investigating the incident at the time, prompting May to rebuke Trump.

"I never think it's helpful for anybody to speculate on what is an ongoing investigation," May said.

Trump has often faced backlash for his approach to violent incidents, especially those inspired by bigotry. After a deadly act of violence at a white supremacist rally in August 2017 in Charlottesville, Virginia, the president was slammed by politicians on both sides of the aisle for blaming "many sides" for what transpired.

While former President Barack Obama was still in office, Trump routinely criticized him for not using the phrase "radical Islamic terrorism" when discussing jihadism.

Shortly after the Paris terror attacks in November 2015, for example, Trump tweeted, "When will President Obama issue the words RADICAL ISLAMIC TERRORISM? He can't say it, and unless he will, the problem will not be solved!"

Trump reiterated this line of attack in June 2016 following the mass shooting at Pulse nightclub in Orlando, Florida, tweeting that Obama should "immediately resign in disgrace" if he doesn't "finally mention the words radical Islamic terrorism."