diplomatic relations/ties
From Longman Dictionary of Contemporary Englishdiplomatic relations/tiesdiplomatic relations/tiesthe arrangement between two countries that each should keep representatives at an embassy in the other’s countryestablish/break off diplomatic relations The two countries established diplomatic relations last year. → diplomaticExamples from the Corpusestablish/break off diplomatic relations• I seemed to have a separate brain for each limb, but they'd all broken off diplomatic relations.