Office of the Director of National Intelligence National Security Council Counselor Peter Kiemel speaks at a House Intelligence Committee hearing on national security implications of climate change on Capitol Hill in Washington, Wednesday, June 5, 2019. (AP Photo/Andrew Harnik)

Senior U.S. and military officials are warning Congress about the potential threat to national security from melting ice in the Arctic.

Officials from the Office of National Intelligence and the Pentagon say climate change will open the Arctic to more ship traffic and commercial activities by Russia and China and create potential sources of conflict.

Peter Kiemel, counselor to the National Intelligence Council, says Russia and China are dramatically increasing their investment there.

Jeff Ringhausen, a Navy official, says that though Arctic shipping is likely to increase, it'll still amount only to a small portion of overall global shipping.

He says the Russian government is "overly optimistic" regarding the increased shipping and investment in the Arctic.

The witnesses spoke at a hearing on impacts on .

  • From left, State Department Bureau of Intelligence and Research Office of Geography and Global Affairs Senior Analyst Dr Rod Schoonover, accompanied by Office of the Director of National Intelligence National Security Council Counselor Peter Kiemel, and Senior Naval Intelligence Manager for Russia and Eurasia Jeff Ringhausen, speaks at a House Intelligence Committee hearing on national security implications of climate change on Capitol Hill in Washington, Wednesday, June 5, 2019. (AP Photo/Andrew Harnik)

  • Senior Naval Intelligence Manager for Russia and Eurasia Jeff Ringhausen speaks at a House Intelligence Committee hearing on national security implications of climate change on Capitol Hill in Washington, Wednesday, June 5, 2019. (AP Photo/Andrew Harnik)

  • From left, State Department Bureau of Intelligence and Research Office of Geography and Global Affairs Senior Analyst Dr Rod Schoonover, accompanied by Office of the Director of National Intelligence National Security Council Counselor Peter Kiemel, and Senior Naval Intelligence Manager for Russia and Eurasia Jeff Ringhausen, speaks at a House Intelligence Committee hearing on national security implications of climate change on Capitol Hill in Washington, Wednesday, June 5, 2019. (AP Photo/Andrew Harnik)

  • State Department Bureau of Intelligence and Research Office of Geography and Global Affairs Senior Analyst Dr Rod Schoonover speaks before a House Intelligence Committee hearing on national security implications of climate change on Capitol Hill in Washington, Wednesday, June 5, 2019. (AP Photo/Andrew Harnik)