The White House has confirmed that President Trump is thinking about lifting sanctions on Russia in preparation for his phone call with President Vladimir Putin on Saturday. Rebuilding relations with Moscow is certainly a worthy goal, but for the United States to benefit from such a move, Washington needs to engage Moscow from a position of strength — and sanctions imposed after Russia’s invasion of Ukraine are central to that.

{mosads}In my 40 years as a U.S. diplomat and NATO official, I have seen many U.S. presidents seek to engage with Russia. While it has never been easy, it was possible to find areas of common ground that increased the security of both sides — as long as the U.S. set clear objectives and stuck with them.

Today, fighting radical Islamic terrorism and stopping the proliferation of nuclear weapons may be areas where increased cooperation is possible. But sanctions put in place due to Moscow’s aggression in Ukraine should not be traded away for cooperation in other areas. That would squander U.S. leverage, and sow the seeds for further instability in Europe.

The sanctions are working. Even if Moscow’s officials say otherwise, Russia is interested in having sanctions removed. Well-coordinated with our European partners and compounded by the decline of global oil prices, the sanctions have had a biting impact on the Russian economy. Its gross domestic product contracted by 3.73 percent in 2015 and 0.76 percent last year. Experts point out that our forceful response also constrained the Kremlin’s actions in Ukraine and helped stop further aggression. And the effects of sanctions will only increase further over time. With presidential elections in Russia looming on the horizon, Putin will need to show better economic conditions for the Russian population.

Trump Willing To End Russia Sanctions In Exchange For Nuke Deal https://t.co/ct1OrAJZBt pic.twitter.com/U72ZoNOxjA

— The Daily Caller (@DailyCaller) January 17, 2017

On the other hand, these measures have had little impact on the U.S. economy or on American jobs. Russia does not even rank among our top 20 trading partners, and prior to 2014, Russia accounted for just 0.71 percent of U.S. exports of goods. For the European Union — for which Russia was the third largest trading partner in 2014, accounting for 8.4 percent of total trade — the impact has been limited and largely reduced due to compensatory measures. According to a recent experts’ report, the drop in exports to Russia in the EU relative to all its outside exports was just 2.8 percent. And, in fact, even those European economies impacted the most, such as Estonia or Poland, have been the most vocal supporters of maintaining the sanctions.

Sanctions should not last forever, of course — they are a means to an end, not an end in themselves. But easing or lifting sanctions should only come if Moscow changes its course on Ukraine — the reason they were imposed in the first place.

McCain: “Reckless” for Trump to lift Russia sanctions https://t.co/4tbwUnTmj3 pic.twitter.com/yyzv5DckKt

— The Hill (@thehill) January 27, 2017

This means, most immediately, the Kremlin halting the violence in Eastern Ukraine and withdrawing all financial, political and military support for its proxies, restoring Ukrainian control over its own borders, and respecting Ukraine’s territorial integrity and sovereignty once again. Ultimately, for all the sanctions to be removed, Russia must end its illegal occupation of Crimea.

Sanctions are not just about Russia and Ukraine. They are about the international world order we live in. If its basic rules are violated — just as they were by Moscow’s actions in 2014 — then our global order turns into chaos. Rule by force would replace the rule of law. This would be hardly conducive to America’s global economic, political and security interests.

Donald Trump three years ago supported sanctions against Russia but now is willing to lift them. https://t.co/TUQV9n3qOk

— USA TODAY (@USATODAY) January 17, 2017

Up until now, there have been few signs that Moscow is ready to reverse its course, but the inauguration of a new U.S. president is an opportunity to put Putin to the test. If it were to lift sanctions without a Russian withdrawal from Ukraine, however, the Trump administration would essentially send a green light to Moscow and other countries that it is content with Russia solidifying its sphere of influence in parts of Europe, or powerless to prevent it. America itself would thus start to undo the post-World War II international order it has helped to build and protect.

The Trump administration should take these realities into account when trying to engage Russia. During their confirmation hearings, we have heard some positive signals from both Gen. James Mattis and Rex Tillerson. They showed an understanding of what is at stake when it comes to our relationship with Moscow. Keeping sanctions in place until Russia takes the necessary steps would put the U.S. in a position of strength in our negotiations, and keep faith with our European Allies who have shared the sanctions burden. Ultimately, there could not be a better starting point in rebuilding our relationship with Moscow on a solid and sustainable basis.

Alexander Vershbow, a distinguished fellow at the Atlantic Council and adviser to Rasmussen Global, was NATO deputy secretary general until 2016 and previously assistant secretary of defense and U.S. ambassador to NATO, Russia and South Korea.

The views of contributors are their own and are not the views of The Hill.