Russian violations of the Intermediate-Range Nuclear Forces Treaty come as a surprise to only those who have not been paying attention to foreign policy in the last few decades.

In a recent National Review piece, Mark Schneider, senior analyst at the National Institute for Public Policy, and Keith B. Payne, former deputy assistant secretary of defense, point out that reports indicating Russian violations have been around since late 2007. Only yesterday did the Obama administration get around to notifying Russian president Vladimir Putin that Russia is in material breach of the treaty.

Observers of Russian history also know Russia has violated almost every major arms control agreement the U.S. has ever signed with it–and  largely gotten away with it. Although the administration’s admission of the Russian violations is admirable, it raises the question of why it waited years before raising the issue with the Russians. Even more strikingly, why did the State Department, which produces an annual report on compliance with treaties, failed to mention any problems related to the INF Treaty implementation in its 2010, 2011, 2012, and 2013 reports?

The most difficult part about arms control agreements is their enforcement and how to bring a non-compliant state into compliance with its arms control obligations. Here are some ways in which the U.S. can respond:

-          Modernize U.S. nuclear weapons and delivery platforms. The U.S. must continue to invest in its nuclear forces, including adequately funding the nuclear-certified bomber, submarine and warhead Life Extension Programs. Deterrence and allied assurance are the key tools in preventing a large-scale nuclear weapons conflict. The U.S. should extend the range of the existing tactical nuclear weapons systems.

-          Advance U.S. missile defense systems. The U.S. needs to build a comprehensive layered missile defense system that would protect its homeland, forward-deployed forces and allies from a ballistic missile threat. With Russia potentially advancing a new class of missiles, the U.S. and its allies, especially in Europe, should start seriously thinking about military implications of these systems.

-          Stop thinking Russia is no longer an adversary. Russia’s recent actions demonstrate it is willing to challenge the status quo in Europe and potentially threaten U.S. interests on the continent. The U.S. should treat Russia as a potential adversary and structure its posture–conventional and nuclear–accordingly.

-          Hold up U.S. implementation of arms control agreements, including the INF Treaty, until Russia is in compliance with its legal and political arms control obligations.

The INF violations are happening in the context of the Russian aggression in Ukraine, which includes providing the rebels with support and an air-defense system that recently shot down a Malaysian civilian airplane; increasing oppression and human rights violations in Russia itself; and extensive nuclear weapons and missile defense modernization. Geopolitically, Russia has been more aggressive vis-à-vis Europe, especially NATO members to the East. The U.S. would ignore these indications at its peril.