The U.S. Navy’s greatest threat might not be coming from either the Russian or the Chinese fleets. Natural disasters, events suggest, could be more threatening. Extreme weather phenomena, such as rising water levels, unseasonal hurricanes, and excessive rainfall — arguably caused by climate change — are jeopardising critical Navy infrastructure, and thus pose a national security danger. For example, in the past decade, the Norfolk Naval Shipyard has flooded nine times, resulting in damages to the shipyard’s equipment and to the ships under repair. And in the past century, the sea level in Norfolk has risen by 1.5 feet, which is twice the global average rate.

The shipyard’s five dry-docks seem to be the most vulnerable. Essentially a waterside bowl that is sealed and pumped dry once a ship enters for repairs, the dry-docks are key for hull and mechanical systems maintenance. If a vessel is unfortunate enough to be caught with its hull opened when extreme weather phenomena strike, then the damage could be catastrophic.

Ray Mabus, Secretary of the Navy under the Obama administration, said that such phenomena could “have the potential for serious, if not catastrophic damage, and it would certainly put the shipyard out of business for some amount of time. That has implications not just for the shipyard, but for us, for the Navy.” Designers have predicted the need for a pumping mechanism that would help contain any excess water coming in. The current mechanism, however, seems incapable of pumping enough water to maintain a water free dry-dock.

And this hasn’t been the only occasion where a weather event proved catastrophic for precious military hardware. Hurricane Michael, which struck in October, significantly damaged 17 F-22, worth close to $6 billion.

The U.S. Navy has four shipyards that are capable of maintaining or repairing America’s nuclear-propelled aircraft carriers and submarines. In addition to Norfolk, there is also the Portsmouth Naval Shipyard, in Maine, the Pearl Harbor Naval Shipyard, in Hawaii, and the Puget Sound Naval Shipyard, in Washington State. Out of the four, the Navy’s 11 aircraft-carriers can only be maintained in the Norfolk and Puget Sound.

But USN infrastructure isn’t the only one under the spotlight. HM Naval Base Clyde, the home port of the British nuclear submarine force, was discovered to have had more than 500 safety violations since 2006, many caused by extreme weather. At least two of them were listed as Category A violations. The British Ministry of Defence describes Category A violations as “actual or high potential for radioactive release to the environment of quantities in excess of IRR99 [Ionising Radiations Regulations] notification limits.” Situated in Scotland, HM Naval Base Clyde has been the launching point for Britain’s underwater nuclear deterrence force.

Retired Vice Adm. Dennis V. McGinn, a former assistant secretary of the Navy for Energy, Installations and Environment, said, “It’s not a question of if, it’s a question of when. And are we going to be standing there saying, ‘oh, we woulda, coulda, shoulda?’”