President Trump, right, during his meeting with China’s Vice Premier Liu He, left, on April 4 in Washington. (Bill O'Leary/The Washington Post)

PRESIDENT TRUMP has been suggesting recently that he’s interested in negotiating a reduction of nuclear weapons stockpiles. After speaking Friday with President Vladimir Putin of Russia, Mr. Trump said they discussed “a nuclear agreement” in which “we get rid of some of the tremendous firepower that we have right now.” On April 4, meeting with China’s vice premier, Liu He, Mr. Trump said, “Between Russia and China and us, we’re all making hundreds of billions of dollars’ worth of weapons, including nuclear, which is ridiculous.” If he’s serious, it is important that Mr. Trump focus on practical measures to reduce the nuclear danger, not negotiating feints.

The Post reported April 25 that Mr. Trump has “ordered his administration to prepare a push for new arms-control agreements with Russia and China.” The exact nature of his order isn’t known, but Mr. Trump is right to be concerned that many areas of nuclear weapons and systems to deliver them are not covered by treaties and agreements. Soon, the 1987 Intermediate-Range Nuclear Forces Treaty between the United States and Russia will be history; the Trump administration pulled the plug, saying Russia violated it with a new, prohibited ground-based cruise missile system. Shorter-range nonstrategic or tactical nuclear weapons, such as gravity bombs, of which Russia has a large stockpile and the United States fewer, have never been covered by a treaty. China, which has avoided nuclear arms control treaties, possesses a relatively small nuclear arsenal of about 300 warheads but has in recent years embarked on an aggressive spree of building new weapons systems, including cruise and other missiles. China has been given a pass for too long, and negotiations could fruitfully bring some transparency and verification to its opaque yet growing might.

All these important and worthy goals for negotiation will be extremely difficult and time-consuming. Before Mr. Trump reaches for the moon, he should tackle extension of the 2010 New START accord with Russia limiting strategic nuclear weapons, which expires in February 2021. This treaty has proved successful and worthwhile, limiting both sides to 1,550 deployed warheads and 700 delivery vehicles; it’s a cap on the most threatening nuclear weapons, those that can span the globe in tens of minutes. If Mr. Trump really wants to avert nuclear dangers, this is the place to begin. So far, he hasn’t done much.

A more worrisome prospect is that Mr. Trump is raising the most difficult nuclear arms control challenges because he knows they can’t easily be addressed. John Bolton, the national security adviser, has criticized international treaties that tie the hands of the United States and once called the New START limits on weapons launchers “profoundly misguided.” Are Mr. Bolton and Mr. Trump really getting ready to roll up their sleeves for more arms control, or is the latest talk just a disingenuous tactic to avoid it?