US President Donald Trump and European leaders have agreed that US Secretary of State Marco Rubio will lead a working group to develop security guarantees for Ukraine, sources say, reports The Wall Street Journal (WSJ).

According to them, this group will comprise national security advisers and NATO representatives. Also, the US will play a coordinating role in the respective discussions.

Security guarantees will include a military presence, air defense, weapons supplies, and monitoring of the cessation of hostilities, European officials told the WSJ.

There are a number of ways that the US can use to provide indirect military assistance to the so-called European peacekeepers, the sources said.

Security guarantees for Ukraine from Europe and the US will be based on the work of a so-called coalition of volunteers, and it may include multinational forces in the future, Bloomberg reports. But the exact format has not been determined yet.