"Spending" is doing a lot of work here. That's not how the national debt works. Spending would imply that there is money changing hands.
Even with regular consumer debt no one is "spending" money on interest if they aren't paying their credit card bill.
You can think of the US debt as more of a "bet" on the US economy and it's military. As long as their is faith in those things the US isn't "paying interest". The only time the "national debt" would matter is if the power and stability are put into question. And, when that happens, it won't matter if the debt is $1 million or $1000 trillion. The world economy will crumble.
The only reason they try to mention this "debt" like it's some loan we are trying to pay back is so they have something to point at when they cut your social security and Medicare to raise the military budget. It's not something that is actually being paid in interest every month.
What's awesome is that the US was using its own ships in hopes Iran would attack them so they could headline "US ships attacked during peace negotiations with Iran!"
Like they can form a narrative that they "win" here no matter which way it went down.
Iran doesn't give a shit if your military does a joy ride through the strait. They are shutting down trade for US and US Ally oil - that's the point. There is no reason to attack US military ships if it doesn't offer a strategic advantage to do so.