Despite early concerns that the arrival of conservative Prime Minister Sanae Takaichi in Tokyo and progressive South Korean President Lee Jae Myung in Seoul could unsettle relations, the two leaders have so far kept alive the rapprochement built by their predecessors.

That alone is not insignificant.

After normalizing ties in 1965, Japan and its erstwhile colony, South Korea, have spent much of the past few decades cycling through historical conflicts, territorial disputes and security mistrust.

Monday marks the 61st anniversary of diplomatic normalization, and while Takaichi and Lee have kept things from sliding backward, experts say they have struggled to turn stability into concrete steps forward.

¡°The two sides have managed to break the cycle of deterioration?but have not created a virtuous cycle that produces tangible benefits,¡± said Shin Kak-soo, a former South Korean ambassador to Japan.

That gap is visible in the economic realm.

Japan and South Korea have both faced tariff pressure from the U.S., their mutual ally, alongside a broader turn toward protectionism and rising vulnerability over global supply chain disruptions. One possible response, Shin said, would be for Seoul to join the Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP), a regional trade pact in which Japan plays a leading role.

The agreement covers 12 economies and accounts for roughly 15% of global gross domestic product. For export-driven South Korea, Shin said accession could help diversify markets and provide its companies with more predictable access to a regional trade framework.

Though Seoul has weighed joining the pact for years, it has hesitated largely due to political sensitivities and opposition from domestic sectors vulnerable to foreign competition.

Earlier this month, several news outlets reported that South Korea had decided to apply to join the CPTPP and was preparing to announce the move as early as late June. But when contacted by The Japan Times, South Korea¡¯s Ministry of Trade, Industry and Resources said ¡°nothing has been decided¡± regarding an application.

The ministry added that the government would continue to review the matter carefully, taking into account stakeholders¡¯ views as well as domestic and international conditions.

Even if Seoul moves ahead, its path to accession could still be complicated by South Korea¡¯s import restrictions on Japanese seafood from Fukushima and seven nearby prefectures, a bilateral irritant imposed in 2013 after the Fukushima No. 1 nuclear disaster.

Approval from all existing members would be needed for South Korea to join the CPTPP, whose food-safety rules also require any import restrictions to be grounded in scientific evidence.

Shin criticized the blanket nature of the import ban, saying Seoul should conduct radiation testing and restrict imports only when specific safety concerns are found, rather than maintaining a broad...