Mozilla announced that the company's Firefox OS will launch in five countries in June 2013 and reach 11 countries by the end of the year.

The Mozilla Firefox OS will make its initial debut in Spain, Portugal, Poland, Brazil and Venezuela in June, but it will not reach the U.S. until at least 2014.

The news comes from Mozilla CEO Gary Kovacs, who made the announcement at the D: Dive Into Mobile summit that AllThingsD is hosting this week (April 15 - 16) in New York City. Kovacs also said the OS is set to launch in six more countries by the end of 2013, reaching a total of 11 countries this year. The CEO made no mention of a Mozilla Firefox OS launch in the UK.

When it comes to the U.S. and certain European countries, Kovacs said that Mozilla Firefox OS will not make its debut until sometime in 2014 at the earliest. Mozilla seems to be keen on focusing on emerging markets first, and launch its new OS elsewhere later on.

As it turns out, Mozilla chose to focus on emerging markets first with the initial rollout of Firefox OS because it would not make sense to launch a "version-one device" in regions where high-end devices grab the spotlight. In other words, the company prefers to lay low for a while and focus its attention and resources on places where Firefox has a strong presence, Kovacs explains.

In strong markets such as the U.S., Firefox OS devices that are primarily low-end would likely go unnoticed now, as the marketplace is mainly interested in high-end handsets. To be successful with Firefox OS, Mozilla needs to test it out in emerging markets first.

"In Silicon Valley we tend to see the world through high-end devices," explains Kovacs. "But that's not true in the rest of the world. So in the short term, we're launching in emerging markets where Firefox is particularly strong ... It didn't make sense for us to launch a version-one device around the world."

As for Firefox OS on the iPhone, Kovacs says that Mozilla's policy is different and its security model, among other things, doesn't mix with iOS. Android will be the mass market platform that Mozilla supports simply because it's much more open. Clearing Firefox OS for use on iOS would imply a policy switch that Mozilla is not willing to make, at least not yet.