keeping up the pressure on its part

Is this so complicated?

I wonder why no one wants to reply this simple question.

It's sort of hard to explain - that's why I didn't answer - I thought someone else who is better at explaining things more succinctly might come along. But I'll take a stab at it.

The way it's written is confusing - especially as it's punctuated - it reads as if North Korea is keeping up the pressure on some part of something.

To avoid the confusion at all - I'd rewrite it like this: On its part, North Korea is keeping up the pressure, in order to raise the stakes.

Or even better: Fulfilling its role (or playing its part) North Korea is keeping up the pressure in order to raise the stakes.

It means they're pushing hard to get what they want, they're trying to make the point that unpleasant things will happen if they don't get their way

Thank you both.
Did you mean NK keeping up the pressure on United Nations, esp its member US?

probably, but your quote doesn't give us that context.