HELSINKI, Dec. 16 (Xinhua) -- Finnish President Alexander Stubb and Swedish Prime Minister Ulf Kristersson said on Monday that talks in Berlin involving European, U.S. and Ukrainian sides had lifted hope toward a possible peace settlement in Ukraine, while stressing that key issues, including territorial questions, remain unresolved.

Stubb voiced cautious optimism about a peace arrangement, telling Finnish media in Berlin late Monday that the coming days and weeks will show whether a solution can be found to what he called "this difficult situation."

He said that the most important development in the past 48 hours had been what he described as a U.S. commitment to security guarantees for Ukraine.

Territorial questions remain the most important unresolved issue, he said, adding that "at least the direction is correct."

At a conference on Monday, German Chancellor Friedrich Merz said the United States had offered security guarantees and that recent diplomatic momentum had made a ceasefire "conceivable."

However, Stubb stressed that the crucial issue would ultimately be whether Ukraine is willing to cede territory in return for security guarantees from the United States.

Kristersson described the Berlin meetings as constructive. In a written statement to a Swedish news agency, he said that Ukraine, the United States and Europe had "for the first time in a long time" sat down together to discuss the possibilities and problems in a peace solution.

Kristersson said many difficult questions remain, "not least about territories and about whether Russia actually wants peace."

"But now there is momentum that is important. We will continue intensive work during the coming days," he said.

Ukrainian President Volodymyr Zelensky arrived in Berlin on Sunday for talks with Merz and other European leaders.

Zelensky also held talks with representatives of Trump during his visit and concluded two days of discussions with U.S. representatives, describing them as "productive" on Monday. Zelensky's talks with Trump's special envoy Steve Witkoff and Trump's son-in-law Jared Kushner lasted several hours on Sunday and Monday.

A group of European leaders, as well as French President Emmanuel Macron, British Prime Minister Keir Starmer and European Commission President Ursula von der Leyen, issued a joint statement on Monday, welcoming "significant progress."

The leaders pledged to work together to provide robust security guarantees, including maintaining Ukraine's armed forces at a peacetime level of 800,000 troops. Enditem