N-UNCOUNT 威吓;(尤指)武力恫吓，武力威胁 If you describe a threat, especially a threat of military action, as sabre-rattling, you do not believe that the threat will actually be carried out. 威吓;(尤指)武力恫吓，武力威胁
It is too early to say whether the threats are mere sabre-rattling.