Online documentation suggests Mugo Pine should not be insulted twice within 12 months. But this Mugo Pine is young, and very bushy, so I decided to prune it anyways. I wanted to reduce the height of the tree, as well as thin it out, such that more light can get into the inner parts of the tree.
The site also suggested that I should try to not remove more than 50% of the foliage. So I pruned some branches off, and hopefully did not kill the tree.
This is what the tree looks like after the much needed haircut.