Russia and Ukraine agreeing in principle to a limited ceasefire deal brokered by the United States this week, instead of a comprehensive one, indicates that the two nations still have disagreements to resolve and a sustainable peace may be difficult to achieve, experts said.

US President Donald Trump's suggestion that his Ukrainian counterpart Volodymyr Zelensky should consider giving the US control of Ukraine's nuclear power plants to ensure their long-term security shows the Trump administration is prioritizing US interests, the experts said.

On Wednesday, after Trump and Zelensky held a phone conversation for roughly one hour, the White House said in a statement that Zelensky requested additional Patriot missile systems and Trump agreed to "work with him to find what was available, particularly in Europe". This, experts added, also shows Trump's reduced commitment to security in Europe.

The White House statement said that Trump and Zelensky had agreed to a partial ceasefire that would cover energy. Zelensky, on the other hand, said he'd also like railways and ports to be protected. However, after Trump's phone conversation with Russian President Vladimir Putin on Tuesday, the Kremlin said the talks on a limited ceasefire referred more narrowly to "energy infrastructure".

So it is clear that the three parties have different views about what the agreement entails, which may act as a stumbling block on the road to lasting peace, experts warned.

Nevertheless, following the US' mediation efforts, Russia and Ukraine said on Wednesday that they had each swapped 175 prisoners in one of the largest exchanges since the conflict started three years ago.

Cui Hongjian, director of Beijing Foreign Studies University's Center of the European Union and Regional Development Studies, said the recent diplomatic efforts have led to some progress in the Russia-Ukraine peace process, with the US actively trying to bring both parties to the negotiating table.

"However, a long-term peaceful resolution of the conflict remains out of reach, given the failure to achieve a comprehensive ceasefire deal and the significant gap between the two sides on territorial disputes and security guarantees," he said.

"Russia did not agree to the US-supported proposal for a comprehensive 30-day ceasefire, opting instead for a limited ceasefire focused on 'energy infrastructure'. This indicates that the US has not achieved any substantial gains in this regard," Cui said.

Zhang Hong, a researcher at the Institute of Russian, Eastern European and Central Asian Studies of the Chinese Academy of Social Sciences, said the failure of the originally proposed comprehensive ceasefire deal highlights that the achievement of goals by the US depends on the willingness of Russia and other parties to cooperate.

"The recent progress in the Ukraine ceasefire is a small but important step in breaking the diplomatic deadlock. While this step holds significant political value, it's still just the beginning. Trump's plan for a quick resolution might face setbacks," Zhang said.

On Trump's remark that "American ownership" of Ukraine's nuclear power plants "could be the best protection for that infrastructure", Cui, from Beijing Foreign Studies University, said such a move shows that in mediating the Russia-Ukraine conflict, the US aims for "dual benefit".

The US wants to advance the peace process for the international prestige it involves, as well as secure control of Ukraine's energy infrastructure and mineral resources to serve its own interests, he said.

"The US is trying to persuade Ukraine to agree to its demand by presenting US cooperation on Ukraine minerals and energy resources as a strategy to deter Russia from damaging these assets," Cui said.

"Securing a role for the US in Ukraine's postwar reconstruction allows the Trump administration the opportunity to tell the American people that it consistently prioritizes American interests," he added.

Cui pointed out that Trump's response to Zelensky's request for additional air defense assistance signals Trump's desire to redefine the US' role on security issues in Europe.

"Traditionally, the US may have acted as a leader, but Trump now believes that European security is primarily Europe's own business, with the US offering, at best, a minimal safety net, as he is reluctant to continue shouldering what he views as the burden of leadership," Cui said.

While Trump wishes to reap profits, he is less willing to contribute than before, which marks a significant shift in the US foreign policy, Cui added.