Following World War I, the Empire of Japan began to expand their range in Asia and the Pacific. Vyner became aware of the growing threats and began to institute reforms. Under the protectorate treaty, Britain was responsible for Sarawak's defence but it could do little, most of its forces having been deployed to the war in Europe against Nazi Germany and the Kingdom of Italy. The defence of Sarawak depended on a single Indian infantry regiment, the 2/15 Punjab Regiment, together with the local forces of Sarawak and Brunei. As Sarawak had a significant number of oil refineries in Miri and Lutong, the British feared that these supplies would fall to the Japanese and thus instructed the infantry to carry out a scorched earth policy.