CREATE TABLE "table1_21636599_1" (
  "period" text,
  "civilians" real,
  "security_forces" real,
  "insurgents" real,
  "total_per_period" real
);

Question: How many insurgents have 602 as the total per period?
SQL: SELECT MAX("insurgents") FROM "table1_21636599_1" WHERE "total_per_period"=602;

Question: How many security forces?
SQL: SELECT MAX("security_forces") FROM "table1_21636599_1";

Question: How many insurgents have 2003 as a period?
SQL: SELECT COUNT("insurgents") FROM "table1_21636599_1" WHERE "period"='2003';