Does Russia China or ObamaUSA have the capability?
As far as I know Russia, China, France, USA, Japan, and possibly India have launch capabilities to put a “big one” in the right spot from offshore. I’m not an expert in booster technology (but that won’t stop me from bloviating on!)
Your run-of-the-mill “city incinerator” missiles have a range of 5000-6000 miles and only rise up 60-70 miles, sort of low for the big EMP pancake effect. The 60 miles high comes in the middle of the trajectory. For good EMP you want to be 120, 170, even 250 miles up, and that would need to be the middle of the path, not the end. Compare that to Korea’s last launch. I think Iran can orbit small sats, they might be capable in a few years.
You need orbital or suborbital capability. Some Russian tests were done at an altitude of 300 miles, that’s the low end of Shuttle territory.
You theoretically could smuggle in, or clandestinely build, a booster in the USA, smuggle in or build a thermonuclear bomb, and launch from Indiana straight up. But for that much effort, the kill is low compared to a thermonuke in NYC hidden in a ‘70 VW microbus painted with flowers.
Or go the Pegasus route, with a missile carried to 40,000 feet on a bomber and launched up from there. But now we are back in First World capabilities.
I don’t think Russia et al would launch an EMP-only attack, because our retaliatory strikes would be unaffected by EMP and they’d lose some space assets. As part of an overall attack policy, they may wish to add to the confusion with a couple EMP-placed nukes, but along with that would come coordinated cyber attacks, conventional nuke missiles, infrastructure attacks, and probably bio attacks too, to lessen any counterstrike.