KITTERY, Maine (AP) -- Vice President Joe Biden says America will follow the terrorists who have killed two journalists "to the gates of hell."

Vice President Joe Biden (Win McNamee, Getty Images)

Speaking at the Portsmouth Naval Shipyard in Kittery, Maine, Biden said Wednesday that the Islamic State militant group responsible for beheading Americans James Foley and Steven Sotloff won't intimidate the United States.

Biden said the American people "are so much stronger, so much more resolved" than any enemy can understand. He says the U.S. won't stop until the militants are brought to justice.

Biden said: "Hell is where they'll reside."

A videotape showing Sotloff's slaying was broadcast Tuesday, two weeks after the same group released a video showing Foley's slaying.

The militants said the killings were in response to U.S. airstrikes against the group in Iraq.

Vice President Joe Biden has received a firsthand look at efficiencies achieved through cooperation and management at the Portsmouth Naval Shipyard.

Union leader Paul O'Connor, who invited Biden, said he wanted Biden to see the collaboration between managers and workers to improve performance. He says such techniques could be used elsewhere in the federal government.

Biden told workers during a tour of training area Wednesday that "this is what industry should do across the board."

Joining Biden at the shipyard on an island in the river that separates Maine and New Hampshire were Sen. Jeanne Shaheen and Rep. Carol Shea-Porter of New Hampshire, along with Reps. Chellie Pingree and Mike Michaud of Maine. Shaheen, Shea-Porter and Pingree are up for re-election, and Michaud is running for governor in Maine.

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