Amid rising tensions, are Trump's nuclear powers unchecked?

South Korea's spy agency says North Korea may conduct more ballistic missile tests by the end of the year to boost its ability to threaten the U.S. Meanwhile, Democrats are asking questions about President Trump's authority to launch nuclear weapons.

The White House considers anxiety about the president's temperament and nuclear weapons misplaced, reports CBS News correspondent Major Garrett. It's North Korea, the administration argues, that is volatile and recklessly provocative. Still, what is legal when it comes to the president and nuclear weapons is a very real topic. 

Mr. Trump's warnings to North Korea have been vivid and descriptive.

"The U.S. has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea," Mr. Trump said in September at the United Nations General Assembly.

The meaning of "destroy" in the nuclear age raises this question: are the president's powers unchecked?

"If you execute an unlawful order you will go to jail," Air Force Gen. John Hyten said.

Hyten, head of U.S. Strategic Command, tried to answer the question over the weekend, saying there are limits.

"I provide advice to the president. He will tell me what to do," Hyten said. "And if it's illegal, guess what's going to happen? I'm going to say, 'Mr. President, that's illegal.' And guess what he's going to do? He's going to say, 'What would be legal?' And we'll come up with options, with a mix of capabilities to respond to whatever the situation is, and that's the way it works."  

Sen. Tom Cotton, R-Ark., said the short time available to respond to a nuclear attack or one that may be imminent gives the commander-in-chief special power.

"The president has to hold in his hands the sole decision to use our nuclear weapons," Cotton said Sunday on "Face the Nation."

Since the Cold War, U.S. presidents have had sole authority to launch nuclear weapons. The codes to do so follow the president in a suitcase: the nuclear football.

"No one human being should ever have that power," Sen. Ed Markey, D-Mass., said.

Now some Senate Democrats want a say in preemptive nuclear war, drafting a bill requiring Congress declare war first.

"The president of the United States is so unstable, is so volatile, has a decision-making process that is so quixotic, that he might order a nuclear weapons strike," Sen. Chris Murphy, D-Conn., said.

The hearing where Murphy spoke was the first of its kind since 1976, when Congress learned in the weeks before he resigned President Nixon was sometimes drunk and depressed, raising alarms about nuclear launch powers and instability in the Oval Office. Mr. Trump's advisers says it is all more stable now and that diplomatic and economic pressure against North Korea remains the first priority.