Could British neutrality shape a US-Japan war?

Would Britain have actively joined Japan in a hypothetical 1914 war against the United States?

Britain was not expected to intervene militarily. Its neutrality could still deny merchant shipping and coal support to both belligerents, sharply limiting an American fleet's ability to cross the Pacific.

Neutral shipping policy could exert leverage without armed intervention. British merchant shipping dominated much of the world's coal movement, especially across Southeast Asia, and Britain could refuse to supply either belligerent while formally treating both alike. The Russo-Japanese War illustrates how access to colliers and reliable coal could constrain a fleet long before battle. An American force larger and more coal-intensive than Russia's Second Pacific Squadron would therefore face a major logistical barrier even if the Royal Navy never fired a shot. Maritime power could operate through commerce and neutrality below the threshold of war.