On 10 December, No 21 Squadron RAAF was withdrawn from Sungai Petani to Ipoh, where it was joined on 13 December by No 453 Squadron RAAF. No 453 Squadron had been sent to protect Force Z on 10 December, but arrived after the warships were sinking. On 15 December both Squadrons were pulled back to Kuala Lumpur, receiving replacement aircraft for those shot down or destroyed. Within the first week of the campaign the Japanese had established air superiority. On 19 December the bombers were moved to Singapore, with No 62 Squadron being re-equipped with Hudsons.