sentences:  Several runways were constructed by US engineers on nearby Owi, while Mokmer Drome was operational by 22 June, and was further improved and expanded with hardstandings for over 100 aircraft throughout July and into August.Other fields were constructed at Borokoe and Sorido, although the latter field was not completed due to limited manpower and unsuitable terrain.These fields were not completed in time for use during operations to capture the Marianas in June, but they were utilized during follow on actions against the Palau Islands in September; Biak was also used to strike targets in Mindanao and in the Netherlands East Indies.