Sabre-rattling, according to Wiktionary, is from the early 20th century when a military officer would threaten to draw his sabre as part of an argument. But the metaphorical meaning is an overt show of military strength to prove a point or to imply a threat. It was recently used by NATO Secretary General Jens Stoltenberg, to accuse Russia of unwarranted “sabre rattling” when Russia declared that it would be adding forty Intercontinental ballistic missiles (ICBMs) to its nuclear arsenal this year. That, of course, in response to increased US activity in NATO allied eastern European countries, which of course, Putin sees as a threat.
“This nuclear sabre-rattling of Russia is unjustified. This is something we are addressing, and it’s also one of the reasons we are now increasing the readiness and preparedness of our forces,” Stoltenberg said.