I guess they could also do something like destroying GPS satellites or undersea cables as well, which might be a better approach if they don't want to kill anyone in NATO countries while hurting them considerably.
I don't see many chances of the US backing down of striking Russia by use of Ukraine, specially as they likely accept their own propaganda that Russia won't or can't do anything, so we unfortunatelly might know soon enough.
Although it would be nice if they could do anything, what about congress and/or other parts of the government that can block the president?
I know that if this happened in my country the president would either have to basically sell the country to get even mediocre laws passed, or more likely with the even farther right congress of now, would get impeached in no time, though I don't know how much of this applies to Sri Lanka.