CREATE TABLE table_71248 ("Date" TEXT, "Location" TEXT, "Nature of incident" TEXT, "Circumstances" TEXT, "Casualties" TEXT)

When was the location 15km NW of Pol-E Khomri, the circumstaances IED and the casualties of 1 WIA?
SELECT "Date" FROM table_71248 WHERE "Casualties" = '1 wia' AND "Circumstances" = 'ied' AND "Location" = '15km nw of pol-e khomri'
SELECT "Date" FROM "table_71248" WHERE "Casualties" = '1 wia' AND "Circumstances" = 'ied' AND "Location" = '15km nw of pol-e khomri'