WASHINGTON -- The U.S. military needs a better Arctic defense policy and has lagged in recognizing it is falling short, Defense Secretary Ashton Carter said in a congressional hearing Wednesday.

Carter's remarks came in response to questions from Sen. Lisa Murkowski at an appropriations committee hearing.

Carter didn't provide details of what might be coming. "But I think a plan that is more than aspirational is needed," he told the panel, offering to work with Murkowski "to that end."

Murkowski and Sen. Dan Sullivan, who is on the Armed Services Committee, have been pushing military leaders in recent months to take Arctic policy more seriously. The lawmakers point to a fairly brief 2013 Arctic strategy and recent reports of large-scale Russian training exercises in the Arctic and a growing fleet of Russian icebreakers. "My concern is that we're well behind the Russians," Sullivan told Gen. Martin Dempsey, chairman of the joint chiefs of staff, in March.

From icebreakers to infrastructure, the United States "may be 40 years behind," Murkowski said at Wednesday's hearing. At last month's meeting of the Arctic Council in Iqaluit, Nunavut, "all anybody wanted to talk about was Russia's Arctic push and what were we going to do," Murkowski said.

The U.S. Northern Command has a report due this spring to inform its operation plan in the Arctic, but its scope is "a little bit vague," Murkowski said. "I think we're beyond the time to be doing plans, and quite honestly I'm not interested in more studies."

Carter concurred with Murkowski's assessment, and said the Arctic "is going to be a major area of importance to the United States strategically and economically to the future."

"I think it's fair to say we're late to the recognition of that," Carter said.