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Reaching some form of compromise between Pyongyang and Washington is essential.
Literal
Pyongyang [and-と] Washington [gen-の] between [at-で] some-kind [gen-の] compromise [to-に] reach [thing-こと] [subj-が] essential [copula-だ].
何らかの 'some kind of' is a formal indefinite marker that leaves the specific form unspecified. ~に至る 'to reach X' is a formal verb for arriving at (an agreement, a conclusion, a state). The nominalizing こと turns the entire clause 'reaching some compromise' into a noun, which is then the subject of 不可欠だ 'is essential.' The で on の間 marks the location/arena where the reaching is to happen.