All Things Digital reported this week that Amazon plans to bring its app store to international markets this summer and the Kindle Fire could be right behind it.

Up until now the app store has only been available in the United States and that of course limits the size of the market. The same goes for the Kindle Fire, Amazon's tablet, which after starting off with strong holiday sales, appears to have trailed off.

In early May, IDC reported that after an initial burst, Amazon had a sharp decline in sales in the first quarter.

"Amazon, which stormed into the market in 4Q11 to grab second place with 16.8 percent of the market on shipment of 4.8 million units, saw its share decline significantly in the first quarter to just over 4 percent, falling to third place as a result," IDC reported in a press release.

As Tricia Duryee pointed out in the All Things Digital post, Amazon opened the App Store 11 months ahead of launching the Kindle in the United States. So, that might mean that there could be a similar delay in the international markets.

But I'm betting there won't be for a couple of reasons. First of all, with Kindle sales flat (to the extent anyone can know that since Amazon does not share sales figures), opening up a cheaper tablet running Android in international markets will very likely boost the sagging sales.

Second, Amazon needed to give its developer ecosystem time to develop apps for the Fire ahead of its initial release. As companies like RIM learned: Releasing the hardware before the apps are ready is a recipe for disaster, but that the apps are already in place it won't require the same ramp-up period as before.

It only makes sense for Amazon to spread out beyond the U.S. market with the Kindle Fire, and this appears to be the first step toward doing that. Amazon's tablet is designed to sell Amazon content, and if it's in more hands, the more content it's likely to sell. It's simple economics.