The Trumps are joined by Barron and the first lady's parents as they return to ...

President Trump and his family arrived back in Washington, D.C. on Sunday evening after spending the weekend at his Mar-a-Lago retreat in sunny Florida. 

The president was seen boarding Air Force One in Palm Beach with his wife, First Lady Melania Trump, and their 13-year-old son, Barron.

Also making an appearance was Ivanka Trump, his daughter; her husband, Jared Kushner; and their children, Theodore, Joseph, and Arabella.

President Trump and First Lady Melania Trump walk along the South Lawn of the White House on Sunday

President Trump and First Lady Melania Trump walk along the South Lawn of the White House on Sunday

The first couple disembarked from Marine One after it landed on the South Lawn. The Trumps were returning to the capital after spending the weekend at the Mar-a-Lago estate in Palm Beach, Florida

The first couple disembarked from Marine One after it landed on the South Lawn. The Trumps were returning to the capital after spending the weekend at the Mar-a-Lago estate in Palm Beach, Florida

The president was joined by his in-laws, Amalija Knavs (left) and Viktor Knavs (right). Last year, the first lady's parents became American citizens

The president was joined by his in-laws, Amalija Knavs (left) and Viktor Knavs (right). Last year, the first lady's parents became American citizens

While Ivanka was tending to Theodore, her husband held the hands of the couple's other two children, Arabella and Joseph. 

The president's youngest son, Barron Trump, was also seen boarding Air Force One with his father.

The 13-year-old Barron has not made many public appearances since his father became president in January 2017.

After landing at Joint Base Andrews following their Florida weekend, the Trumps boarded Marine One for the short flight to the White House.

The president and first lady were seen deplaning from Marine One.

Earlier on Sunday, the president's youngest son, Barron Trump, was also seen boarding Air Force One with his father

Earlier on Sunday, the president's youngest son, Barron Trump, was also seen boarding Air Force One with his father

Barron Trump is seen left following his parents as they board Air Force One at Palm Beach International Airport on Sunday

Barron Trump is seen left following his parents as they board Air Force One at Palm Beach International Airport on Sunday

The president waves as his 13-year-old son, Barron, walks into Air Force One, which will take them back to the Washington, D.C. area

The president waves as his 13-year-old son, Barron, walks into Air Force One, which will take them back to the Washington, D.C. area

The Trumps are seen above disembarking Air Force One after it landed at Joint Base Andrews in Maryland on Sunday

The Trumps are seen above disembarking Air Force One after it landed at Joint Base Andrews in Maryland on Sunday

Ivanka Trump, the president's daughter and senior adviser, holds her son Theodore's hand as they walk from Air Force One at Joint Base Andrews

Ivanka Trump, the president's daughter and senior adviser, holds her son Theodore's hand as they walk from Air Force One at Joint Base Andrews

Ivanka Trump and her son, Theodore

Jared Kushner and two of his children, Arabella (right) and Joseph (seen behind his father)

While Ivanka was tending to Theodore, her husband, Jared, was escorting the couple's other two children, Arabella and Joseph (who is behind his father in the photo on the right)

Ivanka has a tender mother-son moment with Theodore on the tarmac of Joint Base Andrews in Maryland on Sunday

Ivanka has a tender mother-son moment with Theodore on the tarmac of Joint Base Andrews in Maryland on Sunday

The Kushners joined the Trumps for their relaxing weekend at Mar-a-Lago after an eventful week in the nation's capital

The Kushners joined the Trumps for their relaxing weekend at Mar-a-Lago after an eventful week in the nation's capital

Ivanka Trump and her son, Theodore

Ivanka Trump and her son, Theodore

Ivanka Trump stands on the tarmac with her son Theodore at Joint Base Andrews in Maryland on Sunday evening

In tow were the first lady's parents, Viktor and Amalija Knavs. Last year, the Knavs took the oath of citizenship and became American citizens. 

Melania Trump is America's first foreign-born first lady. Her family is from Slovenia.

It is rare for the president's in laws to join him and his family, though it has happened before.

Trump's Mar-a-Lago weekend came after a triumphant week during which his attorney general released a summary of the Mueller report which cleared him and his campaign of colluding with the Russian government. 

The bombshell announcement led Trump and his supporters to declare victory, claiming that he was fully vindicated. 

Trump on Sunday called for an investigation into how the special counsel probe against him and his campaign began, continuing a drum beat against Robert Mueller's look into collusion and obstruction of justice. 

'Everybody is asking how the phony and fraudulent investigation of the No Collusion, No Obstruction Trump Campaign began. We need to know for future generations to understand. This Hoax should never be allowed to happen to another President or Administration again!,' he wrote on Twitter on Sunday.

Trump has railed against the investigation since it ended and cleared him and his campaign of any collusion with Russia in the 2016 election.  

President Donald Trump called for an investigation into how the special counsel probe against him and his campaign began

President Donald Trump called for an investigation into how the special counsel probe against him and his campaign began

Trump has railed against special counsel Robert Mueller's probe ended

Trump has railed against special counsel Robert Mueller's probe ended

Trump tweeted: 'Everybody is asking how the phony and fraudulent investigation of the No Collusion, No Obstruction Trump Campaign began. We need to know for future generations to understand. This Hoax should never be allowed to happen to another President or Administration again!'

Trump tweeted: 'Everybody is asking how the phony and fraudulent investigation of the No Collusion, No Obstruction Trump Campaign began. We need to know for future generations to understand. This Hoax should never be allowed to happen to another President or Administration again!'

Acting White House Chief of Staff Mick Mulvaney said Sunday it was important to find out what went wrong around Mueller's investigation

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