As Russian troops mass on Ukraine's borders and Chinese warplanes harass Taiwan, the Biden administration reiterates "rock solid" support for Ukraine and a possible U.S. willingness to "defend" Taiwan in the event of a Chinese attack.

What is painfully absent from this conversation is the most critical question: Why should the United States risk war with two nuclear powers over these issues?

Certainly, Russia represents a threat to Ukraine. China is not shy in boasting about its ambitions for Taiwan. Equally certain, the U.S., NATO, and our Indo-Pacific allies unequivocally oppose the use of force by a nuclear-armed superpower to consume a smaller, neighboring country. The U.S. and its allies are capable of imposing a significant economic and political cost on either Moscow or Beijing should they move against their neighbor. Yet even if both violated norms and captured Ukraine or Taiwan, the cold, hard reality is this would still not represent a direct threat to the U.S.

Too many people casually throw around words like "Munich" and "appeasement" when someone floats the idea of not going to war with Russia or China over Taiwan or Ukraine. They posit that if one country falls, the aggressor nation will launch a global land grab like Hitler did after being handed Czechoslovakia in 1938.

As I recently discussed in detail, however, the better analogy is the Soviet Union’s invasions of Hungary in 1956 and Czechoslovakia in 1968. The U.S. and the West abhorred and strongly condemned the Soviet Union's actions, but for practical and rational reasons, Moscow’s invasions did not result in any further territorial attacks. Taiwan is a highly emotional issue for the Chinese leaders and has been for over 70 years. Eastern Ukraine has been a friction point between Moscow and Kiev dating back to Catherine the Great in the 1700s. These are special cases.

Yet the U.S. should never base its security on supposition or on promises of any sort from Beijing or Moscow. Our security in those regions of the world is assured by our own powerful Navy, Air Force, and nuclear deterrent. It is further bolstered by our military alliances.

Neither China nor Russia presently has sufficient military capacity to threaten our combined power in either region. While it would be an emotionally unpleasant situation if either Ukraine or Taiwan were taken by force, America and our allies would still be secure and Moscow and Beijing deterred from further attack. It would be the height of folly, therefore, to engage in a war we might not win and which would almost certainly leave us more vulnerable.

Any discussion of using force to prevent China or Russia from taking Taiwan or Ukraine must consider the full ramifications of the risk America would incur by taking action. Especially considering the "what comes next" question. A rational, sober, realistic evaluation of all the factors reveals conclusively that the best course of action for the U.S. is to avoid war with Moscow and Beijing.

We should instead strengthen our conventional and nuclear power to deter either power from directly threatening America.

Daniel L. Davis is a senior fellow for defense priorities and a former lieutenant colonel in the U.S. Army who deployed into combat zones four times. He is the author of The Eleventh Hour in 2020 America. Follow him @DanielLDavis1