Since Russia invaded Ukraine, Western policymakers have worried that, if not handled delicately, their aid to Ukraine could provoke Russia—perhaps even to the point where President Putin ordered the use of nuclear weapons.

The questions in this project are designed as early-warning indicators of potential Russian nuclear use, and were developed by Peter Scoblic, a senior fellow with the International Security Program at New America.

The fear that the Ukraine conflict could spiral out of control is why President Biden ruled out the use of American troops in Ukraine as soon as the war began, saying, "That's called World War III, okay? Let's get it straight here." And his advisers have repeatedly reaffirmed that they have no interest in triggering World War III.

To this point, however, potentially provocative moves—such as Washington's provision of High Mobility Artillery Rocket System launchers, or HIMARS, to Ukraine—have not yielded worst-case fears. Ukraine and NATO have rolled over a number of "red lines" that Putin himself established. "Russian red lines have proven very pink," Jeremy Shapiro, a State Department official in the Obama administration, recently wrote. So, the question now is, what steps might Ukraine or Western nations take that would alter the odds of Russian nuclear use?

This project's questions serve as early-warning indicators, and each implies a second, conditional forecasting question. For example:

If the United States announces that it will supply ATACMS to Ukraine, then what is the probability that Russia will use one or more nuclear weapons?

For some of the project's questions, a resolution should lead forecasters to update their estimates of Russian nuclear use. However, whether they adjust their expectations upward or downward would be a function of their pre-existing beliefs about how wars end and/or escalate.

Peter Scoblic has worked on nuclear security issues for over 20 years. He served as the editor of Arms Control Today, and he is the author of U.S. vs. Them, a history of American nuclear strategy. Dr. Scoblic also served as a senior adviser to Sen. John Kerry, then-chairman of the Senate Foreign Relations Committee, in which capacity he supported the Senate's approval of the New START agreement with Russia.

For other Metaculus forecasts relevant to this project, see the Ukraine and geopolitics—armed conflict category tags.