As Russia continues to flex its military muscle in Ukraine, many worry about a new Cold War. But is a conventional war between the world’s two biggest militaries really in the cards? And if so, how long would such a conflict last?

The Pentagon’s chief of staff, General Milley, recently listed avoiding a Russian-NATO war as the top U.S. priority, warning that the Kremlin would quickly escalate a confrontation with NATO’s much smaller forces. It’s not unreasonable to believe that, given Russia’s limited conventional capabilities and its desire to reassert itself as a global power, a conflict could easily cross the nuclear threshold.

Although both the United States and Russia have reduced the levels of their nuclear arsenals, they still have thousands of warheads capable of destroying large parts of the world. A nuclear exchange, experts say, will negate any real or perceived strengths in other military areas.

In a recent Pew Research Center survey, Americans also reported that Russia was the country they were most concerned about in terms of an escalating international conflict, ahead of China and Iran. This is consistent with findings from focus groups that Pew conducted in 2022, which found that young adults regularly drew parallels between the way Putin treated Ukraine and Xi’s treatment of Taiwan.

Even if the conflict does not turn into full-scale war, a prolonged conflict between the United States and Russia will limit Washington’s ability to pursue other global priorities. For example, the prospects of negotiating a new arms control treaty with Moscow will remain dim as long as the war occupies senior policymakers’ time and resources.