The US will provide defensive assistance to Ukraine and waits for implementation of NATO standards, Reuters reported quoting U.S. Defense Secretary Jim Mattis.

He noted that Washington would continue to put pressure on Russia over what he called its aggressive behavior. 

"On the defensive lethal weapons, we are actively reviewing it, I will go back now having seen the current situation and be able to inform the Secretary of State and the President in very specific terms what I recommend for the direction ahead," Mattis told reporters, alongside Ukrainian President Petro Poroshenko.