Carrot and stick

The phrase "carrot and stick" is a metaphor for the use of a combination of reward and punishment to induce a desired behavior.
In politics, "carrot or stick" sometimes refers to the realist concept of soft and hard power. The carrot in this context could be the promise of economic or diplomatic aid between nations, while the stick might be the threat of military action.
Origin.
The earliest English-language references to the "carrot and stick" come from authors in the mid-1800s who in turn wrote in reference to a "caricature" or cartoon of the time that depicted a race between donkey riders, with the losing jockey using the strategy of beating his steed with "blackthorn twigs" to urge it forward, while the winner of the race sits in his saddle relaxing and holding the butt end of his baited stick. In fact, in some oral traditions, turnips were used instead of carrots as the donkey's temptation.
Decades later, the idea appeared in a letter from Winston Churchill, dated July 6, 1938: "Thus, by every device from the stick to the carrot, the emaciated Austrian donkey is made to pull the Nazi barrow up an ever-steepening hill."
The Southern Hemisphere caught up in 1947 and 1948 amid Australian newspaper commentary about the need to stimulate productivity following World War II.
The earliest uses of the idiom in widely available U.S. periodicals were in "The Economist's" December 11, 1948 issue and in a "Daily Republic" newspaper article that same year that discussed Russia's economy.
In the German language, the idiom translates as "".
Examples.
In the years leading up to World War II and during the war itself, Joseph Stalin applied the "carrot or stick" principle among the nations of the Soviet Sphere of Influence in order to establish tighter control over them. For example, in 1934, Stalin reversed his decision to attack the socialists of the region, instead allowing them to join the "People's Front Against Fascism and War." Despite this alliance's limited success when it came to strategies against the fascism of Nazi Germany, Stalin had effectively replaced the "stick" of aggression that he had been using against the socialists with the "carrot" of a better deal for them: membership in a more sweeping system of Popular Fronts against the Axis.
Stalin's use of reward and punishment, as described above, has not been unique in the world arena. A casual survey of international news confirms that the tactic is still in common use today, by people in power up to and including the presidents of the United States and NATO. 
During the occupation of Czechslovakia during the second world war two infamous SS leader Reinhard Heydrich was noted as having engaged in a "Carrot and stick" method of pacifying the Czechslovakian population, organizing events and picnics for workers and their families while also cracking down hard on any resistance to the german rule in an effort to "Germanize the population".
The carrot and stick as metaphor could be applied to the conduct of the Chinese during the Ming treasure voyages in the 15th century. The carrot was trade opportunity and the stick was the overwhelming naval power that the Ming Chinese expeditionary fleet could bring upon recalcitrant rulers. Diplomatic relationships were based on a mutually beneficial maritime commerce and a visible presence of a Chinese militaristic naval force in foreign waters. The Chinese naval superiority was a crucial factor in this interaction, namely because it was inadvisable to risk punitive action from the Chinese fleet. Meanwhile, the worthwhile and profitable nature of the Ming treasure voyages for foreign countries was a persuading factor to comply.