The White House blocked an Associated Press reporter from an event in the Oval Office on Tuesday after demanding the news agency alter its style on the Gulf of Mexico, which President Trump has ordered renamed the Gulf of America.

The reporter tried to enter the White House event as usual Tuesday afternoon and was turned away, AP executives said. The highly unusual ban, which Trump officials had threatened earlier Tuesday unless the AP changed the style on the Gulf, could have constitutional free speech implications.

Julie Pace, senior vice president and executive editor of The Associated Press, 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 move, 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.

AP Stylebook Used By Thousands of Reporters

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

Demands by a president that a news organization comply with an order to change its content would seem to run counter to the First Amendment of the U.S. Constitution, which bars the government from impeding the freedom of the press.

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.

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.”

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.

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.