Twitter is adding labels to government officials and state-backed media organisations in an attempt to be more transparent.
The changes will allow users to see where a person is tweeting from as well as better understanding the context behind their posts, Twitter said.
It follows similar moves by platforms such as YouTube, which adds labels to the accounts of organisations such as Russia Today, indicating where their funding comes from.
On Twitter, the new feature will initially focus on senior political officials who are the voice of their state abroad and accounts belonging to state-backed media, its editors and senior staff.
The social media platform said that for political figures, the labels would currently only be applied to accounts from the countries that make up the five permanent members of the UN Security Council - China, France, Russia, the UK and the US.
Personal accounts of heads of state will not be labelled.
Twitter also said that state-financed media organisations with editorial independence, such as the BBC or NPR in the US, would not be labelled under the new scheme.
The company said it was an "important step" which would help users when they see an account discussing geopolitical issues "have context on its national affiliation and are better informed about who they represent".
On media organisations, Twitter said: "State-affiliated media is defined as outlets where the state exercises control over editorial content through financial resources, direct or indirect political pressures, and/or control over production and distribution.
"Unlike independent media, state-affiliated media frequently use their news coverage as a means to advance a political agenda. We believe that people have the right to know when a media account is affiliated directly or indirectly with a state actor."
The platform has been one of the most active in taking action against political figures and groups - in 2019 it banned state-backed media advertising and all political advertising - and has recently taken action against tweets from US President Donald Trump for breaching Twitter rules.
Any account given a label under the new programme will be notified and the account owner will be entitled to an appeal, Twitter confirmed.
The company said the labelling scheme is likely to be expanded further over time to cover accounts from a wider range of countries.
The social media site is to also stop amplifying labelled state-affiliated media accounts or their tweets through its various recommendation features.
Additional reporting by agencies