The reporter, whom the AP would not identify, tried to enter the White House event as usual Tuesday afternoon and was turned away. Later, a second AP reporter was barred from a late-evening event in the White House’s Diplomatic Reception Room.

The highly unusual ban, which Trump administration officials had threatened earlier Tuesday unless the AP changed the style on the Gulf, could have constitutional free-speech implications.

Julie Pace, AP’s senior vice president and executive editor, called the administration’s move unacceptable.

“It is alarming that the Trump administration would punish AP for its independent journalism,” Pace said in a statement. “Limiting our access to the Oval Office based on the content of AP’s speech not only severely impedes the public’s access to independent news, it plainly violates the First Amendment.”

The Trump administration made no immediate announcements about the moves, and there was no indication any other journalists were affected. Trump has long had an adversarial relationship with the media. On Friday, the administration ejected a second group of news organizations from Pentagon office space.

Before his Jan. 20 inauguration, Trump announced plans to change the Gulf of Mexico’s name to the “Gulf of America” — and signed an executive order to do so as soon as he was in office. Mexico’s president responded sarcastically and others noted that the name change would probably not affect global usage.

Besides the United States, the body of water — named the Gulf of Mexico for more than 400 years — also borders Mexico.

The AP said last month, three days after Trump’s inauguration, that it would continue to refer to the Gulf of Mexico while noting Trump’s decision to rename it as well. As a global news agency that disseminates news around the world, the AP says it must ensure that place names and geography are easily recognizable to all audiences.

AP style is not only used by the agency. The AP Stylebook is relied on by thousands of journalists and other writers globally.

Barring the AP reporter was an affront to the First Amendment of the U.S. Constitution, which bars the government from impeding the freedom of the press, said Tim Richardson, program director of journalism and misinformation for PEN America.

The White House Correspondents Association called the White House move unacceptable and called on the administration to change course.

“The White House cannot dictate how news organizations report the news, nor should it penalize working journalists because it is unhappy with their editors’ decision,” said Eugene Daniels, WHCA’s president.

This week, Google Maps began using “Gulf of America,” saying it had a “longstanding practice” of following the U.S. government’s lead on such matters. The other leading online map provider, Apple Maps, was still using “Gulf of Mexico” earlier Tuesday but by early evening had changed to “Gulf of America” on some browsers, though at least one search produced results for both.

Trump also decreed that the mountain in Alaska known as Mount McKinley and then by its Indigenous name, Denali, be shifted back to commemorating the 25th president. President Barack Obama had ordered it renamed Denali in 2015. AP said last month it will use the official name change to Mount McKinley because the area lies solely in the United States and Trump has the authority to change federal geographical names within the country.