Senate Democrats on Wednesday couldn't agree that federal debt is a national security problem, in a hearing aimed at assessing the long-term strategic implications of the government's $19 trillion debt.

"A realistic discussion about it, and accepting expert opinion that this debt that we have is not actually right now a threat to our country, is I think a more realistic and honorable way of talking to the American people about it," Sen. Ed Markey, D-Mass., said during a Senate Foreign Relations Committee hearing on Wednesday.

That surprised committee chairman Bob Corker, who concluded the hearing by describing such views as "crackpot," and repeatedly said he expected the panel to demonstrate consensus about the need to limit the debt. Markey also insisted that Republicans drop their interest in changing entitlement programs as they try to mitigate the projected federal debt.

Budget hawks long have warned about a brewing debt crisis, a concern that gained currency in military circles in recent years. "I've said many times that I believe the single, biggest threat to our national security is our debt, so I also believe we have every responsibility to help eliminate that threat," Navy Adm. Mike Mullen, then-chairman of the Joint Chiefs of Staff, said in 2011.

Markey suggested that nuclear weapons represent one of the top targets for such debt reduction. "There's a proposal to [spend] $1 trillion of new nuclear weapon systems in our country over the next 20 years," he said. "That's a crazy number from my perspective."

Former Ambassador Richard Hass countered that such spending cuts would have a minor impact on federal debt. "To use your number: If we're talking about spending $1 trillion over 20 years on nuclear systems, we're talking in 10 years about spending over $1 trillion a year on Medicare. The spending that's driving the debt will not be defense. It's going to be entitlements. Let's not kid ourselves."

Markey didn't dispute those figures, but he said it's politically impractical to cut Medicare.

"When you're going over to entitlement programs, you're talking about grandma and grandpa and you're saying they're the ones that must sacrifice, they're the ones that have to take the cuts," he replied. "Realistically, it's not going to happen. People are not going to step up and say we're going to dramatically slash either Social Security or Medicare or the kinds of Medicaid programs that are going to grandma and grandpa in our country."

Not all Democrats agreed with Markey's views.

"I don't want you to leave with the impression that the Democratic side of this committee is insensitive to the deficit. We're not," said Maryland Sen. Ben Cardin, the ranking Democrat on the panel. "I think Democrats are very concerned that there be adequate revenues in order to be able to make the investments that we think are important for the growth of our nation."

I think Republicans are very concerned that we don't hide the costs of spending, particularly on mandatory spending, and that we have a reasonable foreseeable, affordable programs in the future," Cardin added. "And I think we can listen to each other and learn from each other and pass a blueprint that would not only provide for the economic growth of our country but deal with the security issues ... large uncontrollable debt can compromise America's security, no question about it."