Radosław Sikorski made the remarks at a news conference in Paris, where he met on Wednesday with his French and German counterparts in the Weimar Triangle format.
The discussions included recent statements by the administration of US President Donald Trump about Greenland, an autonomous Danish territory.
Sikorski told reporters on Thursday that US policy on the issue would not be determined solely by the executive branch.
“I would like to know what the position of the US Congress is on this matter,” Sikorski said.
"So far, we’ve heard from individual senators and members of Congress. This is a very important issue for transatlantic relations," he added.
Meanwhile, European Union foreign policy chief Kaja Kallas said EU countries were discussing whether Trump’s statements on Greenland should be taken seriously and how to respond.
She described the developments as "extremely disconcerting" and noted that under the United Nations Charter, the use of force is permitted only in self-defence or with authorisation from the UN Security Council.
The Greenland issue overshadowed Tuesday’s meeting in Paris of the Coalition of the Willing, a group of countries supporting Ukraine.
Sikorski, who later spoke with the US ambassador to France, said Washington could still be relied upon to support Kyiv.
"From what I’ve heard, the United States sees its role in guaranteeing a ceasefire, monitoring any violations and responding if necessary," he told reporters.
While in Paris, Sikorski also held talks on implementing the Polish-French Treaty of Nancy and on bilateral cooperation in security, defence and nuclear energy, officials said.
(pm/gs)
Source PAP