Youtuber Suchomimus* has many brief but informative videos based on commercial satellite imagery of Russian defensive lines being built in recent weeks:<p><a href="https://www.youtube.com/watch?v=B3cceeYu8wA" rel="nofollow">https://www.youtube.com/watch?v=B3cceeYu8wA</a>
<a href="https://www.youtube.com/watch?v=KB-n79HKcU8" rel="nofollow">https://www.youtube.com/watch?v=KB-n79HKcU8</a>
<a href="https://www.youtube.com/watch?v=CtolRDhxy_Y" rel="nofollow">https://www.youtube.com/watch?v=CtolRDhxy_Y</a>
<a href="https://www.youtube.com/watch?v=y0kLBTMk7RE" rel="nofollow">https://www.youtube.com/watch?v=y0kLBTMk7RE</a>