 -- Texas Democratic Rep. Joaquin Castro said President Donald Trump's sharp exchange of warnings with North Korean leader Kim Jong Un “escalated the tension" with the rogue nation.

Castro of San Antonio spoke with ABC News "This Week" co-anchor Martha Raddatz on Sunday in the wake of what appears to be a successful test of a hydrogen bomb by North Korea.

Raddatz asked Castro about Trump's tweets Sunday morning saying "appeasement" doesn't work with North Korea because "they only understand one thing," and about the president's earlier warning that the U.S. would respond with "fire and fury" if Kim Jong Un's regime continued its provocations.

"I don't think that it's been helpful," Castro said. "I don't think that it's helpful to get into a Twitter shouting match with a 32-year-old dictator, Kim Jong Un, in North Korea. I think, unfortunately, that it's escalated the tension and the situation."

Instead, he said, the president "needs to let his diplomats and his military generals and others handle this situation."

The Texas congressman said the best response would be to use sanctions to “choke the economy of North Korea.”

“I think that the best course of action for the United States is to use the significant sanctions that were passed by the United Nations ... and use those sanctions to work with China, work with our allies, and to marshal the world,” the Democratic representative said.

Besides the threat North Korea may pose to South Korea and its other neighbors, Castro said many Americans would also be at risk in the event of military conflict in the region.

"Remember, there's also hundreds of thousands of Americans who live in South Korea and Japan who would be directly in harm's way if there was military action to happen there," he said.

Castro also said the United States needs to continue to shore up its military defenses.

“It would be a time to possibly test our defensive systems,” he said.

If North Korea strikes U.S. allies, "they have to know that we’ll strike back.”