Coast Guard Commandant Adm. Thad Allen, seen in a file photo, planned to address cadets on Thursday.

"These are going to be our future leaders. The last thing you want are your leaders not being tolerant," Rep. Elijah Cummings, D-Maryland, told CNN before heading for the academy with Coast Guard Commandant Adm. Thad Allen.

A 6-inch string tied as a noose was found in an African-American cadet's sea bag in July while he was serving aboard the historic tall ship Eagle.

And during race-relations training in August -- set up in response to the first incident -- a white female civil rights instructor found a small noose in her office at the academy in New London, Connecticut.

"The noose, to African Americans, is a symbol of hatred and it takes us back to the times when African-American people were being hung from trees for no reason at all," Cummings said. "And so it's a very offensive kind of thing."