Joe Biden's press secretary has been slammed for calling Kate the "Duchess of Cambridge", after hearing the news she had been diagnosed with cancer.
On Friday evening, the Princess of Wales released a video via Kensington Palace, where she announced she is undergoing preventative chemotherapy for cancer.
In January, Kate, 42, was hospitalised for 13 days after having planned abdominal surgery.
At the time, Kensington Palace reported that the princess's condition was noncancerous.
Kate announced she has cancer on Friday evening
Reuters / PA
However, tests following the operation showed cancer was present, which Kate revealed in her statement on Friday evening.
Politicians from around the world immediately sent an outpouring of love and kind wishes to the Princess of Wales, including US President Joe Biden.
His press secretary, Karine Jean-Pierre, faced criticism for referring to Kate as the "Duchess of Cambridge", a title she has not officially used since Queen Elizabeth II's death in September 2022.
When King Charles assumed the throne, he bestowed the Prince and Princess of Wales titles to Prince William and Kate.
After hearing the sad news that Kate had been diagnosed with cancer, Jean-Pierre said in a statement: "We've just heard, obviously all of us just heard the terrible news.
The royal did not say which type of cancer she had been diagnosed with
Kensington Palace"Our thoughts are with the Duchess of Cambridge and her family members and friends during this incredibly difficult time.
"And certainly we wish her a full recovery and think it's important that we respect their privacy, especially at this time, so I'm not going to go further than that.
"And obviously we wish the Duchess of Cambridge a full recovery. It is incredibly sad to hear this news."
One royal fan commented: "Duchess of Cambridge? Are you serious?"
Another said: "She is the Princess of Wales! Can you not get anything right?"
Karine Jean-Pierre is the top spokesperson for the Biden administrationReutersA third posted: "I cannot believe how ill-informed and uneducated the White House press officer is.
"HRH The Princess of Wales has not been referred to as The Duchess of Cambridge since The King created William, Prince of Wales, in September 2022."
During Kate's address to the public, she said: "In January, I underwent major abdominal surgery in London and at the time, it was thought that my condition was non-cancerous. The surgery was successful. However, tests after the operation found cancer had been present.
"My medical team therefore advised that I should undergo a course of preventative chemotherapy and I am now in the early stages of that treatment."
The Princess of Wales continued: "This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family.
"As you can imagine, this has taken time. It has taken me time to recover from major surgery in order to start my treatment.
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Kate had 'planned abdominal surgery' in JanuaryGetty"But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be ok.
"As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirit.
"Having William by my side is a great source of comfort and reassurance too. As is the love, support and kindness that has been shown by so many of you. It means so much to us both."
"We hope that you will understand that, as a family, we now need some time, space and privacy while I complete my treatment.
"My work has always brought me a deep sense of joy and I look forward to being back when I am able, but for now I must focus on making a full recovery.
"At this time, I am also thinking of all those whose lives have been affected by cancer. For everyone facing this disease, in whatever form, please do not lose faith or hope. You are not alone."