"Kim Jong Un and North Korea tested 3 short range missiles over the last number of days. These missiles tests are not a violation of our signed Singapore agreement, nor was there discussion of short range missiles when we shook hands," Trump wrote, adding that Kim "does not want to disappoint me with a violation of trust."
"He will do the right thing because he is far too smart not to, and he does not want to disappoint his friend, President Trump!"
Trump's tweets came a day after North Korea launched two short-range ballistic missiles into the sea. The missiles did not appear to pose any immediate threat to the U.S. or its allies in the region, three U.S. defense officials told NBC News.
Earlier this week, North Korea fired two ballistic missiles from the Hodo Peninsula in South Hamgyong province on the country's east coast. The projectiles appeared to be a different type than previous launches, South Korea's national defense minister, Jeong Kyeong-doo, said, according to South Korean news agency Yonhap.
The Pentagon and the White House did not immediately respond to CNBC's requests for comment.
This week's tests come on the heels of an earlier test in July that marked the first provocation since Kim and Trump agreed in June to revive denuclearization talks. A summit between the two leaders in February failed to secure a deal.
North Korea, the only nation to have tested nuclear weapons this century, spent most of Trump's first year in office perfecting its nuclear arsenal. The newest member of the world's exclusive nuclear weapons club has stopped testing of its nukes for now as the U.S. and international community offer the possibility of relief from crippling economic sanctions.
Under the third-generation North Korean leader, the reclusive state has conducted its most powerful nuclear test, launched its first-ever intercontinental ballistic missile and threatened to send missiles into the waters near the U.S. territory of Guam.
Since 2011, Kim has fired more than 90 missiles and had four nuclear weapons tests, which is more than what his father, Kim Jong Il, and grandfather, Kim Il Sung, launched over a period of 27 years.