Trump's nuclear strategy rekindles unresolved debates

The Trump administration last Friday released its Nuclear Posture Review, the first since President Obama's in 2010, raising three big questions.

Why it matters: The chances of nuclear weapons being used are the highest they've been since the Cuban missile crisis. Now is the time for a serious public debate before Congress and the Trump administration decide on a new policy.

1. How much is enough? The NPR calls for updating and augmenting the U.S. nuclear arsenal of 4,500 operational warheads in response to advances by Russia, China, North Korea and Iran. The projected cost is roughly $40 billion a year over three decades, or at least $1.2 trillion in total. This isn’t chump change, especially given competing demands for dollars at the Pentagon and across the federal budget.
2. What new options? Development of low-yield nuclear weapons is another pillar of the NPR. But it's an open question whether they would increase the odds of a nuclear war by lowering the threshold, or decrease them by providing a credible retaliation threat that would enhance deterrence by giving us an option short of all-out conflict.
3. When to use? Per the review, the U.S. might use nuclear weapons under "extreme circumstances" in response to “significant non-nuclear strategic attacks,” including chemical and biological attacks and cyberattacks against U.S. infrastructure or other high-value targets. Whether the U.S. should be the first to use nuclear weapons in any conflict is a critical strategic decision.