Clinton spoke hours after Trump campaign manager Kellyanne Conway, pressed repeatedly on Trump’s plans for the region, said only, “He wouldn’t do what’s being done now.”

“He’s not going to reveal all of his plans and he’s made that very clear. And maybe someone can ask him in a debate,” Conway told “CBS This Morning.” `’But the fact is that this entire world would be put on notice that there’s a strong leader in the White House.”

North Korea’s latest atomic test was its fifth, and the second in eight months. South Korean President Park Geun-hye said the detonation, which Seoul estimated was the North’s biggest ever in explosive yield, was an act of “fanatic recklessness” and a sign that leader Kim Jong Un “is spiraling out of control.”

President Barack Obama condemned the test and said the US would never accept the country as a nuclear power.

In an afternoon speech to a group of conservative activists, Trump used the North Korean development to attack Clinton, describing the situation as “one more massive failure from a failed secretary of state.” He did not say whether he had a plan to address North Korea’s claim the test will allow it to build an array of stronger, smaller and lighter nuclear weapons.

Trump also suggested Clinton and others are wrong to outline their national security policies, because doing so could help the nation’s enemies. “Maybe we shouldn’t be so honest when it comes to military strategy,” he said.

Clinton said the United States would not let North Korea pursue a nuclear weapon and said that as president, she would seek new sanctions in addition to those endorsed by the Obama administration and adopted earlier in the year with the United Nations. She added she would back allies in the region, including South Korea and Japan.

But she also said she would support the kind of negotiations that a group of countries engaged in with Iran over its nuclear program, because sanctions “aren’t enough.” The US must ensure China applies increasing pressure on North Korea, too.

“North Korea poses a threat to the region and poses a threat to the kind of stable border relationship that China has always valued with North Korea,” she said.

The development in North Korea comes at the end of a week in which Trump and Clinton clashed repeatedly over national security.

The New York billionaire attacked Clinton’s record as the nation’s chief diplomat, yet he faced criticism from within his own party for refusing to outline his plans for combating foreign policy challenges, including threats posed by the Islamic State group. Trump said this week that he does indeed have a plan, but would convene military leaders in his first 30 days in office to craft another plan.

Trump has also faced criticism for praising Russian President Vladimir Putin during a high-profile national security forum earlier in the week, and appearing on a Russian-backed television network Thursday evening.

On Friday, Clinton said she was “disappointed” by Trump’s decision to appear on RT America, saying that “every day that goes by this just becomes more and more of a reality television show. It’s not a serious presidential campaign.”

With several prominent Republican national security officials already concerned about Trump’s national security acumen, Clinton has tried to cast herself as the better potential commander in chief. She has aggressively promoted her growing list of military endorsements from both parties.

On Friday, her campaign said the number of retired generals and admirals endorsing Clinton for president has grown to 110. Trump quickly countered by saying his list had ballooned to 120 former US generals and admirals earlier in the week.

Trump’s running mate, Indiana Gov. Mike Pence, received his first intelligence briefing Friday. The vice presidential nominee said he was “grateful” for the “thorough and informative” briefing, but declined to offer any specifics since the information was classified.

Trump was set to appear at a Friday night rally in Pensacola, Florida. Continuing her aggressive fundraising push, Clinton was to appear at two fundraisers in New York. One of them is an LGBT event featuring Barbra Streisand.

Clinton is getting some help from another wealthy backer as well. Billionaire Facebook co-founder Dustin Moskovitz said Friday he’s giving $20 million to help defeat Trump. (AP)