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Traditionally, presidents-elect don't try to make policy before taking office, because the United States has only one president at a time, and on Thursday, Donald Trump spokesman Jason Miller insisted that Trump wasn't trying to set new policy, either, when he tweeted earlier in the day that "the United States must greatly strengthen and expand its nuclear capability until such time as the world comes to its senses regarding nukes." Instead, Miller said, "Trump was referring to the threat of nuclear proliferation and the critical need to prevent it — particularly to and among terrorist organizations and unstable and rogue regimes."

If those two statements — expanding nuclear capabilities and preventing nuclear proliferation — don't seem all that similar, Miller said that Trump "has also emphasized the need to improve and modernize our deterrent capability as a vital way to pursue peace through strength." Some nuclear proliferation experts expressed alarm at Trump's apparent call to start expanding the U.S. nuclear arsenal, after decades of scaling it down, but most analysts were just confused. "It is completely irresponsible for the president-elect or the president to make changes to U.S. nuclear policy in 140 characters and without understanding the implications of statements like 'expand the capacity,'" said Daryl Kimball, the executive director of the Arms Control Association. "He must have leaders around the world trying to guess what he means," Kimball told Reuters. "This is bush league."

Robert Jervis, a nuclear weapons expert at Columbia University, told USA Today he didn't think Trump's tweet would spark a new arms race, as some other analysts fear. But if Trump is going to weigh in on complex issues, especially ones that could lead to massive loss of life, he should be more specific, Jervis said. Is Trump advocating breaking the 2011 New START treaty with Russia? Does he want to spend more than the $350 billion Obama has budgeted to upgrade America's aging nuclear weapons? Has Trump even thought this through? "Unless we're being fooled and he's done great thinking, these tweets are off the top of his head and are immediate responses," Jervis said. "If you try to dig deep there isn't anything there. There's a reason states don't communicate in 140 characters without serious staff work."