The app has come under scrutiny in the past from Republicans, with some stating it has been used to hide illegal immigration.

On Monday, appointments were canceled for people looking to cross the U.S. border just minutes after President Donald Trump took his oath of office.

President Trump on Monday signed an executive order ending birthright citizenship for children of illegal immigrants, likely setting off a legal battle in the courts.

Migrants who waited months to cross the U.S. border with Mexico learned their CBP One appointments had been canceled moments after Donald Trump was sworn in as president.

Mr. Trump is planning to attempt to deny birthright citizenship to the children of immigrants who are in the U.S. illegally, according to the incoming officials. The U.S. government has long interpreted the U.S. Constitution to mean that those born on American soil are citizens at birth, regardless of their parents' immigration status.

President Donald Trump’s plans to curb immigration and beef up border security began taking effect soon after he was inaugurated Monday as he made good on campaign promises.

The orders include declaring a national emergency to deploy military personnel to the border, suspending refugee resettlement and ending birthright citizenship.

"The first 100 days are going to be the most aggressive, change oriented policy proposals and procedures that we've ever seen," KOAT political expert Brian Sanderoff said.

President Donald Trump began his term by taking a series of sweeping immigration executive actions Monday that included declaring a national emergency at the US southern border, immediately ending use of a border app called CBP One that had allowed migrants to legally enter the United States,

“If the US denies legal access or deports significant numbers of immigrants, Uganda stands to lose not only remittances but also the skills and knowledge contributed by these professionals. Under the new order, asylum applications can only begin in Mexico; individuals cannot enter the US and then apply for asylum,” he said.

President Donald Trump has promised swift action on immigration, asylum and border security as he takes office today.