US President Donald Trump has been accused of racism after posting tweets attacking Democratic congresswomen.
He claimed the women "originally came from countries whose governments are a complete and total catastrophe", before suggesting they "go back".
He then said Speaker "Nancy Pelosi would be very happy to quickly work out free travel arrangements".
It comes a week after Ms Pelosi clashed with "the squad", a group of four left-wing Democrat women of colour.
Of the four congresswomen, three - Alexandria Ocasio-Cortez, Rashida Tlaib and Ayanna Pressley - were born and raised in the US, while the fourth, Ilhan Omar, moved to the US as a child.
Ms Ocasio-Cortez was born in the Bronx in New York, approximately 12 miles away from the Queens hospital where Mr Trump himself was born.
What did the president say?
In a three-tweet thread, Mr Trump accused the congresswomen of "viciously" criticising him and the US.
He wrote: "So interesting to see 'progressive' Democrat congresswomen, who originally came from countries whose governments are a complete and total catastrophe, the worst, most corrupt and inept anywhere in the world (if they even have a functioning government at all), now loudly and viciously telling the people of the United States, the greatest and most powerful nation on earth, how our government is to be run.
"Why don't they go back and help fix the totally broken and crime-infested places from which they came. Then come back and show us how it is done.
"These places need your help badly, you can't leave fast enough. I'm sure that Nancy Pelosi would be very happy to quickly work out free travel arrangements!"
He did not explicitly name the congresswomen he was talking about.
However, from the reference to Ms Pelosi it has widely been assumed he was referring to Ms Ocasio-Cortez, Ms Tlaib, Ms Pressley and Ms Omar.
What has the response been?
Ms Pelosi, Speaker of the House, quoted Mr Trump's tweets and described them as "xenophobic".
"When @realDonaldTrump tells four American congresswomen to go back to their countries, he reaffirms his plan to 'Make America Great Again' has always been about making America white again," she said.
"Our diversity is our strength and our unity is our power," she added.
I reject @realDonaldTrump’s xenophobic comments meant to divide our nation. Rather than attack Members of Congress, he should work with us for humane immigration policy that reflects American values. Stop the raids - #FamiliesBelongTogether!— Nancy Pelosi (@SpeakerPelosi) July 14, 2019
Ms Tlaib, congresswoman for Michigan's 13th district, tweeted calling for Mr Trump's impeachment.
"Want a response to a lawless and complete failure of a president? He is the crisis. His dangerous ideology is the crisis. He needs to be impeached," she wrote.
Ms Ocasio-Cortez tweeted at Mr Trump: "On top of not accepting an America that elected us, you cannot accept that we don't fear you either."
You are angry because you can’t conceive of an America that includes us. You rely on a frightened America for your plunder.— Alexandria Ocasio-Cortez (@AOC) July 14, 2019
You won’t accept a nation that sees healthcare as a right or education as a #1 priority, especially where we’re the ones fighting for it.
Yet here we are.
Ms Omar told the president that he was "stoking white nationalism because you are angry that people like us are serving in Congress and fighting against your hate-filled agenda".
She also called him "the worst, most corrupt and inept president we have ever seen".
And Ms Pressley shared a screenshot of Mr Trump's tweet, adding: "THIS is what racism looks like. WE are what democracy looks like."
Others have also flooded the social network with criticism.
If you’ve ever argued that Trump is not a white nationalist, you should find that person and apologize.— Adam Serwer (@AdamSerwer) July 14, 2019
White House reporter Brian J Karem tweeted at the president: "Good morning, racist much?" while Texas congressman Joaquin Castro wrote: "They're Americans. You're a bigot."
US political commentator Josh Rogin said: "This is a new, terrible, racist, sad low, even for Trump."
Bernie Sanders, one of the frontrunners for the Democratic presidential nomination, also accused Mr Trump of racism.
When I call the president a racist, this is what I'm talking about— Bernie Sanders (@BernieSanders) July 14, 2019
We must stand together for justice and dignity towards all. https://t.co/lweeJk7NoF
Mr Trump has not responded to the criticism.
However he has since tweeted about migrants being held at US border detention centres, saying: "Sorry, can't let them into our country."