When South Korean President Lee Jae Myung and Japanese Prime Minister Sanae Takaichi met on Tuesday, they had energy security atop the agenda – and something harder to name top of mind.

It was their fourth meeting in six months, a pace of leaders’ encounters that analysts say reveals much about the uncertainty the two US allies are united in feeling, despite their historical grievances.

The formal pretext of their latest summit was energy security. Japan and South Korea, heavily export-driven and almost entirely dependent on imported energy, are among the world’s most exposed economies to the continuing fallout from the US-Israel war on Iran.

Both leaders signed an agreement on Tuesday establishing a mutual swap arrangement for crude oil, petroleum products and liquefied natural gas, allowing the two nations to provide oil-related products to one another in the event of an emergency supply disruption.

“Recent instability ‌in supply chains and energy markets stemming from the situation in the Middle East has further underscored the need for close cooperation between our two countries,” Lee said in a‌ joint press statement afterwards.