Republican U.S. Rep. Mike Gallagher of Green Bay says there are causes for skepticism when it comes to a deal with North Korean leader Kim Jong Un.

Gallagher, a member of the House Armed Services and Homeland Security Committees, released a series of Tweets Tuesday urging tough talk on North Korea's human rights record.

The tweets are in response to President Donald Trump's

Trump became the first sitting U.S. President to meet with a dictator of North Korea.

"A year ago this month

He was killed by the Kim regime," Gallagher tweeted. "I'm not naive. I recognize that sometimes we have to talk to some unsavory people, but any future negotiations should minimize pageantry and maximize focus on KJU's abysmal human rights record."

Gallagher says a cause for "greater skepticism" includes the risk of giving China an advantage.

He is critical of the administration's plan to end joint military exercises between the United States and South Korea.

"While the suspension of our military exercises is easily reversible, we shouldn't be stopping any joint exercises with our allies," Gallagher says. "These exercises are important to countering China's regional aggression, in addition to Kim Jong-un's hostility."

Gallagher ends by saying he hopes President Trump succeeds. He says he will reject any deal that doesn't mean CVID--complete, verifiable, irreversible denuclearization.

U.S. Sen. Ron Johnson (R-Wisconsin) said the Singapore Summit was a step in the right direction, "but the coming weeks and months will prove whether North Korea is serious in their desire to join the global community."

Johnson also called for complete, verifiable, irreversible denuclearization.