Trump has expressed support for building a larger nuclear arsenal:

President Donald Trump said on Thursday he wants to build up the U.S. nuclear arsenal to ensure it is at the “top of the pack,” saying the United States has fallen behind in its atomic weapons capacity.

Trump is wrong if he thinks that the U.S. has “fallen behind,” which makes the desire to increase the arsenal even more misguided. Building more nuclear weapons wouldn’t necessarily ensure that the U.S. is “top of the pack,” and it would spur Russia and China to do likewise. Ongoing modernization of existing nuclear forces is already far too costly, and this would add even more expense. Trump is always saying that the U.S. doesn’t have the money for various things, so how can the U.S. possibly afford the cost of building more nuclear weapons? Besides being enormously expensive, a violation of existing treaties, and the start of an unnecessary arms race, the U.S. gains nothing from having a larger arsenal. Increasing our arsenal would represent an abandonment of our commitment to arms control, and it would mean undermining the Nonproliferation Treaty (NPT) in the eyes of most states around the world.

The president also referred to New START as a “one-sided deal,” which confirms that he still doesn’t understand what the treaty does and must be relying on briefings from hawkish treaty opponents. Improving relations with Russia won’t get very far if one of the first things Trump intends to do is renege on a major agreement with Russia.