When President-elect Donald Trump enters office in January 2017 he will inherit a transatlantic security environment with major challenges. Russia has used military force to change borders in Europe—something that has not happened since World War II. Since 2008, it has invaded two of its neighbors and it occupies thousands of square miles of territory in Ukraine and Georgia. It is rearming its military, expanding in the Arctic, and threatening the Baltic States. The Trump Administration should take early steps to reassure European allies that America remains committed to the North Atlantic Treaty Organization (NATO). President-elect Trump should recognize that Vladimir Putin is not a partner to the U.S. in the transatlantic region. Most important, Trump should refocus NATO on the alliance’s core mission of territorial defense.

A Stable Europe Is Important to the U.S.

Some of America’s oldest and closest allies are in Europe. The U.S. shares with this region a strong commitment to the rule of law, human rights, free markets, and democracy. Many of these ideas, the foundations on which America was built, were brought over by the millions of immigrants from Europe in the 17th, 18th, and 19th centuries. During the course of the 20th century, millions of Americans have fought for a free and secure Europe.

A stable, secure, and economically viable Europe is in America’s economic interest. For more than 60 years, NATO and the U.S. military presence in Europe have contributed to European stability, which has economically benefited both Europeans and Americans. The economies of Europe, along with the United States, account for approximately half of the global economy. The U.S. and Europe are each other’s principal trading partners. The U.S and Europe are each other’s top source of foreign direct investment. All of this brings untold benefits to the U.S. economy and, by extension, the American worker.

Back to Basics for NATO

NATO was founded in 1949 with the mission to protect the territorial integrity of its members and—if required—defeat the Soviet Union. While NATO’s members are no longer worried about the spread of communism, many current NATO members are certainly worried about protecting their territory from Russian expansion.

The United States needs a NATO that can deter aggression and defend the territorial integrity of its members. Everything else that NATO might do is secondary to this No. 1 mission of territorial defense.

The cornerstone of the NATO alliance is in its founding treaty, which states in Article 5 that an attack on one member is an attack on all members. If the U.S. were to walk away from this commitment, there would be serious security consequences with significant economic implications. If history is any guide, within a generation, the U.S. could again be faced with the choice of sending hundreds of thousands of troops back across the Atlantic to fight a war in Europe to protect America’s interests. After winning the Cold War, this is not the legacy to pass down to the next generation.

In the 21st century, NATO needs to return to basics, with territorial defense as its primary goal. NATO does not have to be everywhere in the world doing everything all the time, and it should shy away from out-of-area military interventions. Rather, NATO needs to be capable of defending its members’ territorial integrity. If the U.S. deems a military intervention outside NATO’s area of responsibility necessary, it should be executed through a “coalition of the willing”—not through NATO.

Defense Is Not Cheap

As a collective security alliance, NATO is only as strong as its individual member states. Only a handful of NATO members can say that they are living up to their spending commitments. The U.S. is right to be concerned by this. However, there is nothing in the 1949 North Atlantic Treaty that states that the alliance’s security guarantee is conditional on a certain level of defense spending by its members.

Since the end of the Cold War, many European nations have consistently cut defense spending, resulting in a loss of significant capability. Last year, only five of 28 NATO member states—Estonia, Greece, Poland, the United States, and the United Kingdom—spent the required 2 percent of gross domestic product (GDP) on defense. In the long term, with the challenges and threats faced by the alliance, this is neither healthy nor sustainable for NATO.

On a positive note, since the Wales Summit in 2014, the annual real-terms change in NATO total defense expenditures has shown a move in the right direction. In 2016, the annual real change for Canada and European NATO members is estimated at 1.5 percent, a $3 billion increase. When cuts have occurred, they have been significantly less than in recent years. In 2015, 19 NATO members stopped cuts to defense spending, and 16 of those 19 also increased their defense spending in real terms.

The Responsible Way Forward

In order to get the alliance back on track the Trump Administration must:

• Lead NATO back to basics. NATO does not have to be everywhere doing everything. It does not have to become a global counterterrorism force or the West’s main tool for delivering humanitarian aid. However, NATO does have to be capable of defending its members’ territorial integrity.
• Reiterate America’s commitment to Europe. President-elect Trump should reiterate that it is in America’s best interest to remain actively engaged in NATO. A peaceful, stable Europe has led to economic, political, and military dividends that have had an immeasurable positive effect on the U.S.
• Take a realistic approach to Russia. As long as Putin remains in power, the experiences of the Bush (43) and Obama Administrations show that Russia will not be a credible partner of the U.S. The Trump Administration should learn from the mistakes of the past instead of repeating them in the future.
• Commit unconditionally to America’s NATO treaty obligations. As long as the U.S. remains a member of the alliance, it must be made crystal clear to any adversary that an attack on one NATO member will be considered an attack on all. Any deviation from this commitment will only invite aggression.
• Lead by example in the alliance and reverse defense budget cuts. Many Europeans use defense cuts in the U.S. as justification for their own cuts. The U.S. should lead by example in the alliance and reverse defense budget cuts in a fiscally responsible manner.
• Press allies on defense spending. Trump did a good job during his campaign bringing attention to the overall lack of defense spending across Europe. However, this issue needs to be addressed without putting America’s commitment to NATO’s collective security guarantee into question.
• Encourage NATO to involve finance ministers. There should be a special session for finance ministers (or their equivalent) at the next mini-summit in 2017. In many parliamentary democracies, the finance minister controls public spending. Educating the finance ministers on the importance of military investment might help secure more defense spending in the long term.
• Set a concrete timeline for achieving NATO benchmarks. While many member states make vague promises about attaining 2 percent of GDP defense spending in the future, few have followed through. The U.S. should encourage NATO members to embed defense spending commitments and timelines in legislation. This will help to increase transparency and political accountability.

America Must Lead

Since its creation in 1949, NATO has done more to promote democracy, peace, economic prosperity, and security in Europe than any other multilateral organization, including the European Union. It is essential that the U.S. continue to be an active participant in the alliance’s future and chart a course back to basics.

—Luke Coffey is Director of the Douglas and Sarah Allison Center for Foreign Policy, of the Kathryn and Shelby Cullom Davis Institute for National Security and Foreign Policy, at The Heritage Foundation.