2020 Democratic presidential candidate Julian Castro on Sunday criticized President Trump for meeting with North Korean leader Kim Jong Un without making any demands of the Hermit Kingdom’s strongman.

Fresh off receiving a boost from his performance in the first Democratic presidential debate last week, Castro used the spotlight to lambast Trump for “raising the profile of a dictator like Kim Jong Un” without any substantive gains being made.

"It's worrisome that this president erratically sets up a meeting without the staff work being done,” Castro said during an appearance on ABC’s “This Week.” “It seems like it's all for show; it's not substantive.”

2020 DEMS CLASH ON 'MEDICARE-FOR-ALL,' IMMIGRATION AT DEBATE MARRED BY TECHNICAL DIFFICULTIES

The former Secretary for Housing and Urban Development added: "I am all for speaking with our adversaries, what's happened here is this president has raised the profile of a dictator like Kim Jong Un and now three times visited with him unsuccessfully because he’s doing it backward.”

Kim is suspected of having ordered the killing of his half-brother through a plot using a nerve agent at a Malaysian airport in 2017. Meanwhile, the United Nations said in May that about 10 million people in North Korea are suffering from "severe food shortages" after the North had one of the worst harvests in a decade.

Castro’s criticism of the president came just hours after Trump and Kim met in the demilitarized zone between North and South Korea and briefly stepped into the north – making him the first sitting U.S. leader to do so.

TRUMP HEADS TO DMZ, DANGLING POSSIBILITY OF MEETING KIM AND CROSSING INTO NORTH KOREA

After asking if Kim wanted him to cross, Trump took 10 steps into the North with Kim at his side, then escorted Kim back to the South for talks at Freedom House, where they agreed to revive the stalled negotiations.

The spectacle marked the latest milestone in two years of roller-coaster diplomacy between the two nations. Personal taunts of "Little Rocket Man" (by Trump) and "mentally deranged U.S. dotard" (by Kim) and threats to destroy one other have given way to on-again, off-again talks, professions of love and flowery letters.

"I was proud to step over the line," Trump told Kim as they met in on the South Korean side of the truce village of Panmunjom. "It is a great day for the world."

Kim hailed the moment, saying of Trump, "I believe this is an expression of his willingness to eliminate all the unfortunate past and open a new future." Kim added that he was "surprised" when Trump issued an unorthodox meeting invitation by tweet on Saturday.

CLICK HERE TO GET THE FOX NEWS APP

As he left South Korea on his flight to Washington, Trump tweeted that he had "a wonderful meeting" with Kim. "Stood on the soil of North Korea, an important statement for all, and a great honor!"

Trump had predicted the two would greet one another for about "two minutes," but they ended up spending more than an hour together. The president was joined in the Freedom House conversation with Kim by his daughter and son-in-law, Ivanka Trump and Jared Kushner, both senior White House advisers.

The Associated Press contributed to this report.