More than 30 countries, including the U.S., Japan and members of the European Union, have imposed far-reaching economic sanctions against Russia in response to the war in Ukraine.

Major Russian banks have been excluded from the SWIFT system, and of the Russian central bank’s $640 billion foreign exchange reserve, the roughly $300 billion in reserves held or managed as dollars, euros or yen by the central banks of the aforementioned countries have been frozen. Countries have also moved to limit as much as possible imports of Russian oil, gas and coal and revoked Russia’s most-favored nation trade status.

In particular, the freeze on Russia’s foreign exchange reserves has been described as the “nuclear option” among financial sanctions, as it prevents Russia from accessing funds it could use to prop up the plummeting ruble. Yet Vladimir Putin recently boasted that “the strategy of the economic blitz has failed” and noted the ruble had bounced back to pre-crisis levels. The ruble has indeed rallied to approximately the same level as before the Ukraine crisis began.

On the other hand, economic sanctions have just begun. And Russia’s war has become a quagmire. If there are further massacres of Ukrainian civilians or if Russia uses tactical nuclear missiles, its frozen foreign exchange reserves may be liquidated altogether. Economic sanctions are also likely the strongest card Ukraine can play when negotiating a cease-fire or even a peace agreement with Russia. We should thus count on these sanctions remaining in place for the long term. U.S. sanctions against North Korea and Iran have continued for 17 and 15 years, respectively.

Nevertheless, we must recognize the major challenges that accompany economic sanctions against Russia — a nuclear power. Sanctions may strangle the Russian economy and intensify domestic criticism of Putin. The Russian military, however, is highly resistant to the effect of sanctions, as it is self-sufficient in terms of both munitions and oil. Moreover, the Russian treasury takes in $1 billion in energy-related revenue every day. It has also been reported that “neutral countries” like India are buying Russian oil and gas at discounted prices.

The more important question is the purpose of economic sanctions against Russia. Are they intended to end the war? To bring about Putin’s downfall? Or are they aimed at changing the Russian political system itself?

We must ascertain the trade-offs and cost-effectiveness of sanctions. Do economic sanctions hurt ordinary citizens more than the political system under which they live? Or could sanctions end up damaging the countries that impose them even more than the country they target? It is not clear to what extent the Group of Seven and other countries imposing sanctions against Russia have discussed these issues or developed a shared strategy. As things stand, there is a real risk that, in the event of a protracted war in Ukraine, these “sanctions allies” will fall out of step with one another.

It was the League of Nations, formed after the end of World War I, that decided to justify economic sanctions intended to preserve the international order and associated rules by punishing aggressor nations (Article 16 of the Covenant of the League of Nations). U.S. President Woodrow Wilson, a proponent of the League, explained the nature of sanctions as “something more tremendous than war,” and their effect as “an absolute isolation that brings a nation to its senses just as suffocation removes from the individual all inclinations to fight.”

In the 1930s, however, Germany and Japan challenged the League of Nations system. And when they began to invade other countries, the League’s economic sanctions could not function as intended. Against the backdrop of the deepening Great Depression, every country feared that greater economic interdependence would leave it vulnerable to economic sanctions and leaned toward self-sufficiency and protectionism.

Japan and Germany invaded Southeast Asia and Central Europe to secure their access to strategic resources such as oil before embargos were put in place. We must thus remember that economic sanctions carry the risk of provoking their targets to military action.

A series of U.S. sanctions against Japan, imposed after the termination of the U.S.-Japan Treaty of Commerce and Navigation in 1939, offer a dramatic demonstration of this risk. Following the Japanese invasion of northern French Indochina in September 1940, the U.S. placed an embargo on the sale of scrap metal to Japan.

In July 1941, all Japanese assets in the U.S. were frozen. Later that same month, Japanese forces invaded southern French Indochina, and in August the U.S. responded by placing an embargo on oil exports to Japan. The oil embargo in particular robbed those within Japan’s ruling class who favored appeasing the U.S. of the room to maneuver politically to break the diplomatic deadlock between the two countries.

The Roosevelt administration believed the oil embargo would either force Japan to concede or prompt it to invade the Dutch East Indies. Japan’s military leaders, on the other hand, became obsessed with the idea that the country should seize its fleeting time advantage and make a preemptive strike on the U.S. before its oil reserves were depleted.

In “Pearl Harbor 1941: The First Energy War,” Charles Maechling, Jr. writes, “Oil was not the primary cause of the steady deterioration of relations between the United States and Japan, but once employed as a weapon, it made hostilities inevitable.” At the time, Japan relied on U.S. imports for more than 80% of its oil supply.

Yoichi Funabashi is chairman of the Asia Pacific Initiative and a former editor-in-chief of the Asahi Shimbun. This is a translation of his column in the monthly Bungei Shunju.