Combat during the Siberian intervention was far more mobile than combat seen in the western front during ww1. The eastern front as a whole never really devolved into wholesale end to end trench warfare even before the exit of Russia from the war. The main factor limiting mobilization was not enemy trench lines or fortifications. Instead it was the punishing enviroment of Siberia, its under developed road network, and its (by the time of the siberian intervention) damaged railroad network. Though damaged most of the fighting concentrated around railroad stations of vital importance as without these neither side could effectively logistically support their advances. The almost non existent and divided Russian navy and the lack of manned or supplied coastal fortifications also made allied amphibious landings way more viable than during the western front in ww1. Thus any attempt by the red forces to entrench themselves along the coast was quite useless. The allies and white forces had complete superiority near the coast not only due to the possibility of using their navy to go around red trenches but also because of the ability of the allied navies to provide constant fire support against red advances. Coastal road networks near port infrastructure was also relatively better maintained than further into the country, allowing the allies and white forces to employ armored cars to great use against red infantry. In short the conflict was quite mobile moving from railroad station to railroad station and following the few well established and undamaged road networks. The use of trenches was limited to the immediate defence of an area, town, city, or fortress. The whites were effectively outnumbered and the reds cut off various white formations by capturing surrounding railroads and blocking off road networks then allowing the punishing environment and lack of supplies to do the rest, effectively forming a siege without having to litteraly surround the area in question.