China has imposed new visa restrictions on foreign journalists working for U.S. news companies as its latest retaliatory action in an escalating dispute. Both countries are engaged in tit-for-tat sanctions in a trade dispute that has to date trickled down into sectors such as technology, finance and the news media.

Last week, several journalists said they were no longer able to immediately renew their credentials. The routine process typically takes just days and foreign journalists are immediately given new credentials valid for 12 months. However, several reportedly received letters saying their applications were still being processed and that they would have to use the letter as proof of their professional identity.

Journalists' China visas are directly tied to their professional identity cards. Without the renewed credentials, visas held by foreign journalists have two months' validity only.

Authorities said visas and news credentials may be revoked at any time - which means journalists have no real way of determining how long they can stay in the country. According to a CNN report, reporters and other journalists known to receive the letters were those working for large U.S.-based news organizations.

One reporter said authorities had informed him the move was in no way related to the stories that his company was publishing but were instead in retaliation for the Trump administration's treatment of China journalists in the U.S. The same journalist said their work had remained unhindered and the only change was in the visa validity.

In May U.S. authorities shortened the validity of visas for China journalists in the country to 90 days only. Despite pleas from China, officials in the U.S. have yet to clarify the status of the visa extension applications submitted by China journalists. Without an official response, China journalists will be forced to leave the country in November.

On Sunday the U.S. State Department issued a statement in response to China's decision saying it was troubling. The agency added that actions against foreign journalists would serve only to worsen the reporting environment in China. State Department representative Morgan Ortagus said the latest action was further proof China was "afraid" of independent and investigative reporting.

"Beijing's actions prove time and again that the (ruling Chinese Communist Party) is afraid of independent and investigative media reporting that has only broadened and deepened the world's understanding of China for the better."