Facebook is giving another feature that clones Snapchat Stories a big push.

Facebook Stories, a feature that puts photos that disappear after 24 hours at the top of the Facebook mobile app, is rolling out to users in Chile, Greece and Vietnam, Facebook confirmed. However, it is not available to users in all markets. The feature was first tested among users in Ireland in January and its extension this week comes hot on the heels of a major Facebook offensive to bake Snapchat’s core features into its main mobile services.

Messenger Day was launched inside the Messenger app last week, targeting the app’s one billion-plus monthly users with a feature that frustrated many by sitting right at the top of the app. Having already introduced similar features in WhatsApp in February and Instagram last year, Facebook is applying its Snapchat cloning to its main mobile app, which accounts for most of the 1.7 billion people who use Facebook on mobile each month.

I wrote last week that Facebook has gone too far with its efforts to throw Snapchat’s core functionality into WhatsApp and Messenger since it doesn’t match with the appeal or usage of either service. Facebook’s core mobile app could be different. People are expecting to see images inside the social network, but the concept of 24-hour disappearing photos may be new to many of those 1.7 billion mobile users who don’t use Snapchat or Instagram Stories.

On the subject of Instagram, Facebook looks to be enjoying considerably more success with Instagram Stories, its take on Snapchat inside the photo sharing service. The feature has reached 150 million daily users, according to Facebook, which makes it the same size as Snapchat, while it also appears to have stolen users and high-profile influencers from Snapchat, too.

The focus of Instagram is visual content and a large chunk of the audience is young people, so there seems to be overlap with Snapchat and significant growth potential. That said, many people remain unconvinced that Facebook’s Snap-cloning in WhatsApp and Messenger is a positive addition.

Note: An earlier version of this post stated that Facebook Stories was rolling out worldwide, however Facebook confirmed that the expansion is to three more countries.