Suppose Kim Jong Un wants to attend a United Nations meeting in NYC

Suppose that Kim Jong Un, dictator of North Korea, decided that he wanted to attend an assembly of the United Nations at its headquarters in New York City, in person. What legal, practical or diplomatic obstacles might prevent him from doing so?

None.

Maybe some. The US government has occasionally made noises about denying UN speakers entry into the US for those it deems terrorists and such. But it’s usually worked out.

I don’t think that’s quite true. I think a country has the option of refusing to accept somebody’s diplomatic credentials. So the United States could legally refuse to grant entry to Kim Jong-Un.

That’s true but doesn’t the US have an obligation as the host nation of the UN to allow all member states and their representatives access? Wouldn’t it be a transgression of the UN Charter to deny Kim Jong-Un entry?

The US allowed Fidel Castro and Yassar Arafat address the UN in the past. As host nation, the US is obligated to allow any diplomat the UN certifies to travel to the UN, even if the US does not recognize the government.

Kim is far too paranoid.
I don’t know if any NK Head Of State has addressed the UN.

Arafat addressed the UN in 1974 but in 1988 the Reagan administration denied him a visa to speak at the General Assembly in New York. Instead, the General Assembly convened at the Palace of Nations in Geneva to hear him speak. I don’t know if Kim could be excluded the same way. Unlike the PLO, North Korea is a member of the General Assembly.

That’s my understanding. The US can put limitations on their movements (ie no leaving NYC w/o approval from the State Department), but they have to be allowed in.

Young Un seems to be reluctant to ever leave home, for fear somebody at home will take over and not let him come home.

The US promised the UN when the headquarters was sited in NY to allow foreign diplomats to enter the US to go to the UN.

I don’t know that this is any legal obligation, but most administrations have followed this. When Reagan refused in 1988, the UN responded by moving as a body to Geneva Switzerland for the session. And that was kind of a hint that they could decide to move the UN headquarters entirely to Geneva – after all, that was one of the top rivals for a headquarters location back when the UN was deciding, and there are still a lot of UN agencies run out of Geneva (like the World Health Organization, International Telecomm Union, etc.).

They not only allowed Castro to address them, but didn’t they even let him wear his sidearm while doing so?

Around 25 years ago, I worked for a small company that did some minor subcontracting work for NASA and the military. We were in Pleasantville, in the middle of Westchester County (the county immediately north of New York City). During one of the regular visits from the Defense Investigative Agency rep, we were given wallet-sized cards listing certain license plate prefixes. We were told that if we saw a car that far north with diplomatic license plates and the number started with one of the prefixes listed on the card, we were to report that to a certain number. The idea was that representatives of certain countries were restricted to something like a 25-mile radius around the UN headquarters and we were outside that circle.

BTW, that DIA rep seemed bored, because he lingered a lot after his inspection. (I can’t imagine that Westchester County was or is a hotbed of spies.) A couple of times, I prompted him for stories about espionage.

Arafat wore an empty holster.

North by Northwest: was that Westchester or Long Island?

Long Island. Also fictional.

Just within the last few years the US denied a visa to Iran’s chosen ambassador to the UN. He was involved (or at least claimed he was involved) in the hostage crisis.

Here is a State Department analysis of the UN HQ Agreement.

TL;DR
The US maintains the right to refuse visas. Doing so carries risk and could backfire as with Arafat in 1988.

However with N Korea, the issue is complicated by the fact that i) the War is still technically not over and ii) The UN is itself a belligerent.

That’s interesting, however it doesn’t stop North Korea having a permanent representative to the UN:

“Backfire” is in the eye of the shooter.