In the wake of the U.S. efforts’ to restore full ties with Cuba, South Korea is seeking to put back on track its own relations with the old Cold War foe while renewing hopes for a possible change in North Korea.

Washington and Havana have agreed to reopen their embassies in each other’s capitals, following a surprise announcement last December that they will reestablish the bilateral diplomatic relations after 10 months of secret talks.

Seoul, which itself has been working to improve its relationship with the Caribbean country, welcomed the move, calling for Pyongyang, a longstanding ally of Cuba, to change course and follow suit.

“We expect that the restoring of the U.S.-Cuba relations will provide an opportunity to usher in an era of new cooperation and open the door for peace and prosperity for Cubans,” South Korea’s Foreign Ministry said in a statement. “North Korea, too, will hopefully join the positive flow in the international community through the right choice.”

In contrast, ties between North Korea and the U.S. have rather been plummeting this year on the back of the communist country’s ongoing nuclear weapons development, stringent verbal attacks and suspected hack on Sony Pictures over a film about a plot to kill North Korean leader Kim Jong-un.

U.S. President Barack Obama has said before and during the early years of his presidency that he was willing to thaw relations with North Korea, Iran and Cuba. In a 2007 election debate, he said it was “ridiculous” to think that “somehow not talking to countries is punishment to them, which has been the guiding diplomatic principle of this administration,” referring to the then-presidency of George W. Bush.

Yet skepticism persists over any fresh restart of talks, while Obama said after the hack that he would “review” whether to relist Pyongyang as a state sponsor of terrorism.

With Cuba off Washington’s blacklist, North Korea will remain the only remaining vestige of the Cold War on the terrorism list. The other three listed countries are Iran, Sudan and Syria.

North Korea and Cuba were seen as sharing much in common. Both the small communist states weathered the collapse of the Soviet Union in the early 1990s and its aftereffects, faced stifling U.S.-led international sanctions and carried out family power successions in recent years.

And they had apparently maintained close cooperation until recently. Late last year, Havana proposed a resolution at a U.N. panel to defend Pyongyang’s human rights record and counter a European Union-led text calling for justice for the perpetrators including Kim.

In July 2013, Panamanian authorities intercepted a North Korean ship carrying arms from Cuba. The Latin American country initially reported the cargo as economic handouts in the form of sugar, but under the giant bags were two Cuban MiG-21 fighter jets, missiles and other equipment, which constituted a breach of U.N. Security Council resolutions.

The gap between the two longtime allies is only set to continue widening. While Havana enjoys an easing of sanctions, economic aid and high-level exchanges with Washington and the world community, Pyongyang will likely face deeper isolation over its grave human rights situation, nuclear weapons and other asymmetric warfare programs.

Any return of North Korea to the terrorism list means more sanctions on trade, investment, assistance, financial transactions and other engagement with the reclusive country.

For Seoul, this could spell a greater dilemma as it is poring over ways to improve cross-border relations such as through a lifting of bilateral bans, restart of tours to Mount Geumgangsan and expansion of trilateral economic cooperation including Russia.

Alarmed by the recent progress between the U.S. and Cuba, Pyongyang has dispatched Kang Sok-ju, secretary of the Central Committee of the North’s ruling Workers’ Party, to Havana apparently to reaffirm their decades-long friendly relationship with Cuban President Raul Castro.

By Shin Hyon-hee (heeshin@heraldcorp.com)