“The Supreme Court upheld Birthright Citizenship, which is too bad for our Country, but we can easily make it up in Congress through Legislation, with the support of the President, that has now been determined during this process,” Trump said in a Truth Social post. “No long and unwieldy Constitutional Amendment is necessary! Congress should start TODAY to work on ending expensive and unfair to our Country, Birthright Citizenship. They will have my Complete and Total Support!”

Trump also posted a link to an article on Truth Social earlier on Tuesday, suggesting that his efforts to end birthright citizenship could happen with or without the Supreme Court’s approval.

The highly anticipated ruling, which experts had expected to go against Trump, comes after Trump signed an executive order last year, on the first day of his second term, to end birthright citizenship. Established by the 14th Amendment, birthright citizenship grants automatic citizenship to anyone born in the U.S., no matter the immigration status of their parents. At the signing of his order last January, he said that birthright citizenship is “absolutely ridiculous.”

When oral arguments in the case took place in April, Trump attended, becoming the first sitting president to do so.

Trump has claimed that the U.S. is the only country that offers birthright citizenship, but that’s false. More than 30 other countries also offer some version of it.