Hillary Clinton during an interview with Business Insider. Sam Rega/Business Insider Former Secretary of State Hillary Clinton gave a blistering critique on Thursday of GOP presidential frontrunner Donald Trump's emerging geopolitical worldview.

"Of course not," she told Henry Blodget, Business Insider's CEO and editor-in-chief, when asked whether she had confidence in Trump's ability to lead the military. "No, of course not."

In the interview at Purchase College in New York, the Democratic frontrunner painted Trump's foreign policy as dangerous, out of step, and "illegal."

She made specific mention of two of Trump's statements that have drawn scrutiny in recent days: his dismissal of the North Atlantic Treaty Organization alliance as "obsolete" and his suggestion that he might allow Japan and South Korea to develop nuclear weapons in exchange for an ease in US defense commitments to the countries.

"These are incredibly dangerous ideas that need to be confronted," she said.

Clinton also criticized Trump for embracing military tactics that are prohibited under international law. Trump has advocated targeting the families of terrorists and bringing back waterboarding, though he has more recently softened his stances on those positions.

"His suggestions are not only offensive but, in certain cases, dangerous and sometimes even illegal, like his dismissal of the laws of the United States international law when it comes to torture," she said.

Watch Clinton's comments below:

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Trump's diplomacy has come under increased scrutiny since last week's terrorist attacks in Brussels, which left more than 30 people dead and hundreds more injured. Since then, he has unveiled a slew of policy pronouncements, most notably in a lengthy New York Times interview.

Many national-security experts cast doubt on the effectiveness of Trump's plans. They have cast his suggestion that he might be open to a nuclear-capable Japan and South Korea, for instance, as a dangerous proposition with the propensity to fuel a regional or global nuclear arms race.

"It would be a free-for-all," Jeffrey Lewis, the director of the East Asia Nonproliferation Program at the Middlebury Institute of International Studies, told Business Insider earlier this week. "It would be a giant science experiment that I would not want to see."

Clinton told Business Insider she had received messages from "bewildered" world leaders who were concerned about Trump's rise and rhetoric.

"They want to know what's going on," she said. "And the amount of publicity that he gets, the coverage that he gets — so he said some very ill-considered dangerous thing, and it's around the world in a nanosecond."