“We are concerned that the president of the United States is so unstable," Sen. Chris Murphy (D-Conn.) said. | Steve Helber/AP Senators: Should Trump have sole nuclear launch authority?

Senators considered Tuesday for the first time in more than 40 years whether the president should continue to have the sole authority to launch a nuclear attack — a question that comes amid increasingly saber-rattling rhetoric between Donald Trump and North Korea leader Kim Jong Un.

“We are concerned that 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 that is wildly out of step with U.S. national security interests,” Sen. Chris Murphy (D-Conn.) said during a Foreign Relations Committee hearing that yielded few clear answers about checks on the commander in chief's power. “Let’s just recognize the exceptional nature of this moment.”


Though Republicans were not as vocal about their concern, some did express worry that one person alone can make the decision to launch a nuclear war.

Committee members questioned former military and administration officials about what checks and balances Trump would face if he were to order a so-called first strike nuclear attack, in which the U.S. was not imminently under attack. Some lawmakers suggested that the president should have to come to Congress to get approval for this type of attack.

The president has almost sole authority to launch nuclear weapons under the current process. That system was designed during the Cold War to allow haste, given that a Soviet attack would allow only about 30 minutes before impact.

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But the nuclear landscape has changed since then: The U.S. now faces threats from smaller, less stable nuclear-armed countries, though they probably cannot launch the kind of large-scale attack that could preemptively wipe out America's land-based nuclear arsenal. Questions have also emerged about whether Trump might consider a nuclear first strike on North Korea, especially after his promises to meet threats from Kim with “fire and fury” and "total destruction."

Sen. Ben Cardin (D-Md.) said he worried that Trump was considering using a nuclear weapon against the Hermit Kingdom in an effort to avoid the hundreds of thousands of casualties that a conventional conflict would inflict on Japan and South Korea.

“It boggles the rational mind,” said Sen. Ed Markey (D-Mass.). “I fear that in the age of Trump the cooler heads and strategic doctrine that we once relied upon as our last best hope against the unthinkable seem less reassuring than ever.”

But retired Gen. C. Robert Kehler, the former head of U.S. Strategic Command, said checks exist on any president who orders a nuclear strike absent an imminent attack on the U.S.

Kehler said that in his former position, he would have questioned and ultimately refused to follow an order from the president to launch a nuclear weapon if it seemed illegal or not a proportional response. He said that would be especially true in the case of a preemptive attack where an attack was not imminent and more time could be spent on the decision.

“I would have said I have a question about this and I would have said I’m not ready to proceed,” Kehler told the panel.

All members of the military are required to follow legal orders, but are also required to reject an illegal order on any matter, including a nuclear strike.

Sen. Ron Johnson (R-Wis.) said that provided him “a little comfort.”

“So we can have a little comfort that, even though president has the authority, there are limits to that in the context when there’s time,” he said.

Peter Feaver, a professor at Duke University and former National Security Council official, said that in situations where the military is waking up the president in the middle of the night to warn of an incoming attack, a prescribed chain of events would unfold in which the president has the sole authority to decide whether to launch a counter strike.

But in a situation in which the president is waking up the military — “I’m mad and I want to do something about it” — it would require more than just the commander in chief to launch a nuclear weapon.

“The president alone could not effect the strike. He would require lots of people cooperating with him to make the strike happen,” Feaver said. “They’d be asking questions that would slow down that process.”

Meanwhile, Sen. Jeanne Shaheen (D-N.H.) said she's especially worried about the role the president's Twitter feed could play in a nuclear conflict, saying Trump's use of social media increases the need for Congress to have a voice in authorizing a potential first strike. Earlier this year, North Korea said Trump had declared war on the country with a tweet that said Pyongyang's leaders won't "be around much longer."

Brian McKeon, a former Pentagon and NSC official, agreed with her assessment.

"I would be very worried about a miscalculation based on continued use of his Twitter account with regard to North Korea," he said.

CORRECTION: An earlier version of this report incorrectly attributed two comments about the chain of events in a nuclear strike decision. They were made by Peter Feaver, a professor at Duke University and former National Security Council official.