Cardin doubled down on his questioning of Kehler asking, "If you believe that this did not meet the legal test of proportionality, even if ordered by the president of the United States to use a nuclear first strike, you believe that because of legalities you retain that decision to disobey?"
"Then what happens?" asked Sen.
Corker, who has announced he won't seek re-election next year and has become a frequent Trump critic, has said he would use his committee chairmanship to keep the President in check.
Ed Markey, a Democratic senator from MA who is sponsoring legislation that would limit the president's authority to launch a first nuclear strike, said he was not reassured by Kehler's arguments.
The president and his top officials have said repeatedly that North Korea would not be allowed to threaten the United States with nuclear weapons, but as Pyongyang has persisted with its nuclear and missile tests, it has been unclear what the administration would do to stop the regime.
Other senators also focused on Trump's use of Twitter, especially his ongoing tweeted attacks at North Korean leader Kim Jong Un.
Democratic Sen. Chris Murphy of CT seemed to agree during the hearing when he addressed the panel.
Multiple senators argued that the President's loose Twitter finger could have catastrophic consequences.
Other former national security officials testified that if there isn't an imminent attack, it would be more hard for the president to launch a nuclear attack out of the blue. Feaver, who has served under two presidential administrations, was formerly on the National Security Council for President George Bush. "There would be a large group of advisers and legal advisers weighing in on this". "Many Americans fear that the president's words could turn into nuclear reality", Sen.
"In the past" Feaver said, "Congress has played a vital role in pushing the Executive Branch to strengthen the nuclear command and control system, and the time may be ripe for another close look".More news: Serena Williams Stuns In First Post-Baby Appearance
More news: Volvo owner buys flying-car making Terrafugia
More news: Advance Auto Parts jumps after profit beat
On Tuesday, former officials cautioned that adding Congress to the equation would hamper the U.S. response in a high-stress scenario without a lot of time.
"I would have said: I'm not ready to proceed", Kehler said.
Adding the extra layer would lead to "conflicting signals" that "can result in loss of confidence, confusion or paralysis in the operating forces at a critical moment", Kehler said.
Not since 1976 has Congress held a hearing to debate the president's authority to use nuclear weapons. Gerald Ford was president.
On the issue of the President being able to start a nuclear war, he was very direct; "Even in the absence of a nuclear attack against our country, no one can tell the president 'no.' Not Secretaries Mattis, or Tillerson". "You'd either get a new secretary of defense or get a new commander".
As commander-in-chief, Trump has the sole authority to order a nuclear strike from land-based missiles, nuclear submarines and bombers. During his recent trip to the region, however, Trump dialed back the rhetoric and said he hoped North Korea would "come to the table and make a deal" and back down from its nuclear aims.
"We are concerned that the president 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", Mr Murphy said in Congress.
But he is not legally obligated to consult with anyone.
U.S. President Donald Trump's power to launch nuclear weapons is under scrutiny by both Republicans and Democrats in Congress concerned over his comments about striking North Korea. Much of the Senate committee hearing was taken up by discussion of what constituted an imminent threat and who could make that determination. "I think it will be very informative to the American people and the rest of the Senate about what powers the President has - should, shouldn't have, whatever".
"I think that we have to keep trust, keep faith in the system that we have that has proven effective now for decades", he said.