NATO's flirtation with adding 2 more members runs the risk of starting a war the US can't afford to fight

• While in Europe this month, Defense Secretary Lloyd Austin made clear that Ukraine and Georgia may still join NATO.
• Ukraine and Georgia have much in common with other NATO members - including a rivalry with their neighbor, Russia.

US Secretary of Defense Lloyd Austin is visiting Europe this week having said Ukraine and Georgia have an "open door to NATO" and that "no third country has a veto over NATO's membership decisions."

Because both countries have been on the receiving end of Russian aggression, it is natural to feel sympathy for Ukraine and Georgia - but offering them NATO membership is an extremely dangerous and counterproductive policy that does not serve the US national interest.

Rather than bolster the security of the American people, as one would expect US defense policy to do, expanding NATO increases the risk of the United States being drawn into a war with Russia. Moving forward in the process of offering NATO membership to Ukraine or Georgia risks igniting a major NATO-Russia conflict.

Should an attack follow Ukraine or Georgia's formal acceptance into the alliance, NATO's Article 5 would legally require the United States to militarily intervene. Such a scenario could quickly escalate to the nuclear level, making it imperative that the conceivably devastating consequences of NATO enlargement are honestly assessed.

Unfortunately, Austin's comments are just the latest example of US policy makers failing to accept the geopolitical reality of eastern Europe.

The 2008 Bucharest NATO Summit was a significant turning point for European security. There, it was formally announced that Ukraine and Georgia would eventually become members of the alliance.

In response, Russian Foreign Minister Sergei Lavrov told reporters "We will do all we can to prevent Ukraine's and Georgia's accession into NATO and to avoid an inevitable serious exacerbation of our relations with both the alliance and our neighbors."

Other top officials went further, with one Russian general saying, "Russia will take unambiguous action toward ensuring its interests along its borders. These will not only be military steps, but also steps of a different character." In other words, Moscow made it clear that either country's entry into the alliance would cross a red line and Russia would be prepared to use all facets of power, including military intervention, to enforce that red line.

Russia made good on its promise. In 2008 it fought a five-day war with Georgia and established de facto control of the breakaway regions of Abkhazia and South Ossetia. In 2014, Russia annexed Crimea and provided military support to pro-Russian separatists in eastern Ukraine.

Moscow effectively created buffer zones in both countries that separate Russia's borders from Western-backed governments. It has also cunningly ensured that both conflicts remain frozen, using the threat of further escalation as a potential hedge to prevent NATO accession.

Americans need only look at our own history to understand why Russia has acted in this manner. The United States established the Monroe Doctrine in the early 1800s, claiming that any intervention by European powers in the western hemisphere would be viewed as an act hostile to the United States.

By the end of the 19th century, the United States had successfully driven out all other great powers and established itself as the regional hegemon of the New World. When the Soviet Union challenged the US position in 1962 by deploying military assets 90 miles off the coast of Florida, the world was brought to the brink of nuclear Armageddon.

If the United States does not tolerate such behavior, why does the Biden administration believe that expanding NATO - and therefore the presence of US troops - on Russia's borders will be viewed by Moscow as benign?

Providing hope to Kyiv and Tbilisi that NATO will come to its defense also creates a moral hazard problem. Rather than making the difficult political accommodations necessary to end their respective conflicts, Ukrainian and Georgian leaders are incentivized to shift their security burden on the United States by taking a hardline stance against Moscow.

This escalates US-Russia tensions and is not particularly kind to average Ukrainians and Georgians, who would likely bear the brunt of any renewed conflict.

The reality is that Moscow views the prevention of Ukraine and Georgia from joining NATO as a core strategic interest. As such, Russia will go to great lengths to achieve this objective. The Biden administration should conclude that it is not worth risking World War III over two countries with little geopolitical significance.

As the United States shifts its focus to the larger strategic threat of China, US policymakers would be wise to seek détente with Russia. Such an effort would start by taking Ukrainian and Georgian NATO membership off the table.

Sascha Glaeser is a research associate at Defense Priorities. He focuses on US grand strategy, international security, and transatlantic relations. He holds a master of international public affairs and a bachelor's in international studies from the University of Wisconsin-Madison.