Five U.S. states are moving forward with a lawsuit against Washington.

The states demand steps be taken to prevent Asian carp from reaching the Great Lakes.

Legislation approved last month requires the U.S. Army Corps of Engineers to complete a plan for shielding the lakes from the invasive carp within 18 months.

A quicker timetable is one of the requests in a suit filed three years ago by Michigan, Wisconsin, Minnesota, Ohio and Pennsylvania.

The states also want a guarantee that the corps ultimately will sever a man-made link between Lake Michigan and carp-infested waters near Chicago.