Last week, North Korea test-fired two new short-range ballistic missiles, its first missile test since leader Kim Jong Un and US President Donald Trump met last month and agreed to revive denuclearisation talks.
Dubbed the KN-23, the missiles are created to evade missile defence systems by being easier to hide, launch, and manoeuvre in flight.
Pompeo will also be seeking in Bangkok to ease brewing tensions over trade between US allies Japan and South Korea that threaten to disrupt Seoul's electronics industry and draws on long-standing bitterness over Japan's actions toward Korea during World War II.
North Korea ended a two-year pause in missile tests in May, with a series of short-range launches.
"Treasury continues to enforce existing sanctions against those who violate United Nations Security Council resolutions ... and evade US sanctions on North Korea's unlawful nuclear and ballistic missile programs", the agency added. In the first talks after the Singapore summit, Pompeo was snubbed by Kim, and after he left, North Korea accused him of making robber- or gangster-like demands. According to Reuters, a North Korean official also says working-level denuclearization talks between the two sides will start very soon. Referring to the previous launches, Iwaya said, "It is extremely regrettable that North Korea continues firing the missiles that violate the United Nations resolutions".
"We can't say at this point how far they flew and are analysing them while preparing for additional possible launches", the official told AFP.
The White House, the Pentagon and the U.S. State Department did not respond immediately to requests for comment.
It said both missiles were believed to have flown about 250km (155 miles) at a maximum altitude of 30km (19 miles) and that South Korean and USA militaries were trying to find more details of the launches.
The DMZ meeting was the third summit between Trump and Kim since they first met in Singapore past year.
"These missiles represent technological developments that threaten US allies and forces in Asia", he said. He added that North Korea needed to stop conducting these launches. He said North Korea fired "standard" missiles that many countries possess. Pyongyang will carry out more launches before the drills begin next week and again afterwards, he predicted.
Pompeo said on Tuesday he did not anticipate that the North Koreans would be in Bangkok but, if they were, he would look forward to a chance to meet Ri.
The Korean Central News Agency (KCNA), North Korea's state-run news service, highlighted musical performances to honor the cult of the Kim family this week featuring songs titled "Cantata to Marshal Kim Il-Sung", the founder of communist North Korea, and "Off We Go, Brindled Ox".
The agency said Pyongyang sent up a "multiple unidentified projectiles" early on Wednesday morning. Trump has said of the meeting that he and Kim "fell in love". So, if we can help them find a good place for each of their two countries, we certainly find that important to the United States, indeed, as well as to each of those two countries.