Beled-Xaawo and Mandera are pretty much a single town.
For example, my little abtiyaal (my mom's father took another wife in Beled-Xaawo in the mid 90's) live in Beled-Xaawo but go to Mandera for school. My first cousin whose mother lives in Beled-Xaawo bought his mother a considerable space in Mandera and setting a bakhaar now. My paternal first cousins whose mother moved to Africa bought land and built their mom a villa in Mandera.
Beled-Xaawo was extremely insecure the last 22 years and thr last major war was the one which removed Al Shabaab. Beled-Xaawo is coming back up having depended a lot on Mandera but a considerable amount of wealth, property, and investment in Mandera also belongs to people from Beled-Xaawo.
All in all you can say combined they are a single large town with one side on Somalia side of the border and the other on Kenya side of the border.
I always knew Mandera was a border town but I didn't know Balad Xaawo was spilling over into the Kenyan side nor did I think Mandera was literally footsteps from Somalia.
Is there a large Kenyan government presence there apart from a few border patrol agents and police? Do the locals regard themselves as "part of Somalia" despite the border?
It is a large town. They have an official "customs post" but its like a stand smack dab in the middle of the union of the two towns. You can easily go in an out without caring for it. They can't ever close the traffic and cross between the two towns if they ever tried. Everytime fighting happened in Beled-Xaawo it spilt into Mandera despite Kenya army.
This video is from Mandera when Al Shabaab and Gedo forces had their last fight in Beled-Xaawo (beginning of Al Shabaab loss)
Honestly it is not longer about Somali nationalism but clan political power. By that I mean these guys live great with each other and do business and stuff but "rer Somalia" in the twin cities is Marehan and "rer Kenya" in the twin cities are all non-Marehan.
Marehan don't want these guys sharing "Gedo" therefore "Somalia" political power with them and the non-Marehan are very satisfied having the Marehan outside of the Kenya constituency equation that exists between them.