Days after President Trump shifted his tone on Ukraine, Defense Secretary Pete Hegseth participated in a meeting on Monday of the roughly 50 nations supporting the embattled country.

The meeting was held virtually and led by the defense ministers of Britain and Germany.

The collection of countries, which is known as the Ukraine Defense Contact Group, was founded during the Biden administration by Defense Secretary Lloyd J. Austin III. But Mr. Hegseth has largely taken a hands-off approach, ceding leadership of it to Britain shortly after Mr. Trump took office in January.

When the contact group met in person at NATO headquarters in April, Mr. Hegseth opted to call in. He did not participate in the next meeting, which was in June.

Mr. Trump initially expressed deep skepticism of giving U.S. military support to Ukraine, which Russian forces invaded in 2022. But last week, he said the United States would help Europe send more weapons to Ukraine and warned Russia that if it did not reach a peace deal within 50 days, he would impose a new round of punishing sanctions.

A spokesman for the Pentagon declined to comment on Monday regarding Mr. Hegseth’s role in Monday’s meeting. The Defense Department said in a statement that it would not comment on internal discussions between the administration and partner nations.

A senior American official, speaking on the condition of anonymity before the meeting to discuss internal planning, said the United States expected “several countries” to commit to purchasing additional “capabilities” — weapons, munitions and equipment — to donate to Ukraine.