Military chiefs from the United States and a number of European countries on Thursday presented options to their national security advisers for providing security guarantees to Ukraine, officials said.

This followed U.S. President Donald Trump's pledge to help protect the country under any deal to end the three-and-a-half-year conflict in Ukraine.

A Pentagon statement said U.S. and European planners had developed the military options for "appropriate consideration" by allied national security advisers. Reuters was first to report that the military leaders were preparing the options.

The chiefs of defense for the United States, Finland, France, Germany, Italy, United Kingdom and Ukraine met in Washington, D.C., between Tuesday and Thursday.

A source familiar with the matter said U.S. Secretary of State Marco Rubio, who also serves as Trump's national security adviser, held a conference call on Thursday with his European counterparts to discuss the options.

Final details must still be worked out, the source said, but European countries would provide "the lion's share" of any forces involved in security guarantees for Ukraine.

That echoed Vice President JD Vance's comment on Wednesday that Europe would need to shoulder "the lion's share" of the costs of the operation.

"The planning work continues," said the source, adding that Washington still was "determining the scope of its role."

Trump has said he will not deploy U.S. troops in Ukraine but has left the door open to other U.S. military involvement, including air support.

Troop deployments

One option would see European boots on the ground in Ukraine but putting the United States in charge of their command and control, sources have told Reuters.

U.S. air support could come in a variety of ways, including providing more air defense systems to Ukraine and enforcing a no-fly zone with U.S. fighter jets.

French President Emmanuel Macron and British Prime Minister Sir Keir Starmer have both supported troop deployments as part of a coalition of the willing, with German Chancellor Friedrich Merz also signaling openness to his country's participation.

The head of Germany's soldiers' union said on Thursday that European NATO leaders must face the reality that tens of thousands of troops would need to be deployed in a Ukraine peace force for the long term.

Trump has pressed for a quick end to Europe's deadliest conflict in 80 years, and Kyiv and its allies have worried he could seek to force an agreement on Russia's terms.