What are the current regulations for foreigners crossing the Mae Sot border into Myanmar?

Mae Sot border update: I was finally able to get Mae Sot immigration on the phone after trying to contact them unsuccessfully on a direct number for over a week. Finally, I was re-directed to a different number by someone who monitors the Tak immigration Facebook page, with an official answering right away.

The news is both positive and negative, depending on your circumstances.

Firstly, the bad news. Foreigners aren't allowed to cross the border to travel into the interior of Myanmar. Thais aren't allowed to either. Thais are allowed to travel to Myawaddy township only on a day return basis with or without their vehicles.

Foreigners like us are only permitted to cross the bridge for the purposes of a border run. We aren't allowed to visit Myawaddy even for the day, as was previously permitted.

So if anyone happens to be in the area and needs to do a border run (sometimes known as a visa run though strictly speaking that's something different) then that's the only thing permitted. You'll be required to wait in the office while your passport is stamped and then asked to return immediately to Thailand.

It's not known when the security situation improves to the point that foreigners are allowed to visit the town. I find it strange that Thais are allowed but not foreigners, but Myanmar has never been a country that made any sense (though it's a fascinating place), so that's it. Border runs = permitted, depending on your nationality. Visits to Myawaddy and travel into the interior of the country = prohibited at this time.