On April 13, eight Republican senators sent a letter to President Trump, urging him to take action against Russia’s violations of international sanctions against North Korea. The letter mentioned allegations that Russia helped North Korea export supplies related to chemical weapons to Syria. Nor is this violation an isolated case. Moscow continues to illegally export oil to North Korea and to hire North Korean guest workers for construction projects in Siberia.

Why is Russia ignoring the international agreement to isolate Kim Jong Un until he reverses his country’s nuclear program? Some prominent scholars, including Vladivostok-based Asia-Pacific security expert Artyom Lukin, argue that it’s because Moscow wants to preserve its historical alliance with North Korea.

That could be — but there’s still more to it. My research suggests that violating the sanctions is part of Russia’s broader goal of challenging U.S.-led sanctions regimes, for two reasons. First, the two powers have very different perspectives on what constitutes an effective sanctions policy. Second, Russian President Vladimir Putin wants the political benefits of resisting U.S.-led sanctions policies toward North Korea.

Russia’s view of what makes sanctions effective is very different from the U.S. view

At the United Nations, Russia has consistently voted for U.S.-led sanctions proposals against Pyongyang. But Moscow’s unofficial policy toward these sanctions differs markedly from Washington’s. The United States has often viewed sanctions as a tool of coercive diplomacy and a mechanism to weaken the political foundations of rogue regimes. By contrast, Russia believes that sanctions should be used only as punitive measures against specific violations of international law and should not completely isolate the targeted country economically.

Kremlin policymakers like Russian Foreign Minister Sergei Lavrov have explained the reasoning for this restrictive approach to sanctions against North Korea. Excessively stringent punitive measures, Lavrov argues, could destabilize North Korea by weakening its economy — leading North Korea into opting for belligerent actions such as its Nov. 28 missile launch; the projectile landed in Japanese waters. By contrast, Russia believes that restraint will persuade North Korea to play nice with its neighbors.

That’s why, as part of its general resistance to sanctions against North Korea’s civilian industries, Moscow helped North Korea evade oil-related sanctions. In early 2017, Russia opposed the United States’ proposed oil embargo against North Korea, and at the United Nations, successfully worked with China to change these to more moderate oil industry sanctions. When the United States successfully lobbied for further restrictions on North Korea’s access to foreign oil in a December U.N. resolution, Moscow ensured that North Korea would not be isolated from global energy markets by shipping enough oil to Pyongyang to reduce petroleum prices in North Korea by 60 percent.

Further, that is why Russia has criticized the U.S. government’s unilateral sanctions against North Korea. For instance, Moscow condemned as “illegitimate” the March 7 U.S. sanctions against North Korea for using VX nerve gas to kill Kim Jong Un’s brother Kim Jong Nam.

Russia has further worked to prevent other countries — especially South Korea — from adopting similar unilateral sanctions. For instance, on Sept. 4, 2017, South Korean President Moon Jae-in requested Russia’s assistance in resolving the North Korea  nuclear crisis. Just one day later, Putin argued that implementing further sanctions would be “ineffective.” And when Seoul refused to impose new sanctions on North Korea during the PyeongChang Olympics, the Russian Academy of Sciences’ Georgy Toloraya, an influential security expert, praised South Korea’s restraint.

Putin is shoring up his internal support

Besides directly challenging U.S. sanctions proposals, Putin has also ignored — or encouraged — Russian businesses when they violate existing sanctions on trade with North Korea. The Russian government has helped use the port of Nakhodka in eastern Siberia as a shipment point to North Korea, as this is part of Moscow’s stated strategy of expanding Russia’s trade relationship by a factor of 10 from 2010 to 2020.

[North Korea has a big tuberculosis problem. It’s about to get worse.]

Putin has facilitated these sanctions violations because he wants to ensure the loyalty of anti-Western nationalists in Russia’s security services and foreign policy establishment — factions that could undermine his power.

That is an approach that has been in place since the Soviet Union’s collapse in 1991. After the 1991 Gulf War, anti-Western nationalists in Russia stridently opposed the international community’s near-complete embargo against Saddam Hussein’s Iraq. These nationalists pressured Russian policymakers to violate U.S.-led embargoes against other Kremlin-aligned countries such as Yugoslavia and Iran.

Some pro-Western officials, like then-Russian Foreign Minister Andrei Kozyrev, ignored these powerful groups and aligned Moscow with U.S. sanctions policies to improve relations with Washington. For instance, Kozyrev went along with the 1992 vote for sanctions against Moammar Gaddafi’s Libya, and supported an embargo against Serbia during the Bosnian War.

Anti-Western nationalists were outraged at what they saw as betrayals of long-standing Russian allies and unacceptable sacrifices of Russia’s national interests, undermining Moscow’s oft-repeated claims that it is a crisis-proof ally. The criticism was successful. Then-President Boris Yeltsin dismissed Kozyrev in 1996.

The risks of going along with the United States only increased as the U.S.-Russia relationship deteriorated. In 2011, Dmitry Medvedev, Putin’s predecessor as president, signed on to U.N. Resolution 1973, which authorized a humanitarian intervention against Gaddafi’s Libya in 2011. Anti-Western nationalists stridently criticized Medvedev for his acquiescence to a NATO military intervention in Libya and restricted his influence over foreign policy decision-making after Putin, who opposed the Libya intervention, returned to the presidency in 2012.

To stay in power, Putin needs the loyalty of these anti-Western factions within Russia’s Federal Security Service (FSB) and military-industrial complex. And so he has actively considered the opinions of these groups in his sanctions policy toward North Korea.

To preempt internal opposition, Russia has imposed punitive measures against North Korea, such as the proposed expulsion of guest workers by 2019, that are difficult to enforce. This strategy allows Moscow to look as if it is taking action against North Korea — but without actually taking measures that harm Siberian businesses dependent on North Korean guest workers or that greatly restrict North Korea’s access to hard currency.

Putin’s consistent defiance of international sanctions against North Korea rallies anti-Western nationalists around his regime, while also carrying out Russia’s vision of moderate sanctions that are more likely to nudge Kim Jong Un in the right direction. The West can expect the Russian government to continue to prevent the complete isolation of North Korea for the foreseeable future.