The Congressional Research Service, a nonpartisan arm of Congress, reported that between 1995 and 2008, the United States provided North Korea with over $1.3 billion in assistance.
CRS reported that "slightly more than 50 percent for food aid and about 40 percent for energy assistance." The funding was distributed from the end of Bill Clinton’s first term to the final year of George W. Bush. $666 million were given during the Clinton administration.
The portion for food aid was aimed at patching the chronic malnutrition faced by large portions of the North Korean population, as a result of famine and inequalities perpetuated by the dictatorship.
The United States provided energy funds of $549.7 million in two chunks to North Korea, one between 1995 and 2003, another between 2007 and 2009. From the context of his remark, it seems Trump was talking about the first stream under Clinton.
That’s the 1994 Agreed Framework, negotiated between the United States and North Korea amid threats from Pyongyang to pull out of the Nuclear Nonproliferation Treaty.
In the treaty, North Korea agreed to halt production of plutonium, which is used for nuclear weapons. The country halted plutonium processing in Yongbyon and froze construction of two other reactors.
In return, an international consortium would replace North Korea’s plutonium reactor with two light-water reactors, mostly financed by Japan and South Korea, to provide the energy without nuclear capability. Meanwhile, the United States agreed to supply heavy fuel oil.
The two light-water nuclear reactors were never built. The United States nonetheless provided North Korea $400 million in heavy fuel oil until 2003. The money was distributed by the Korean Peninsula Energy Development Organization, the organization established to implement the Agreed Framework.
When Clinton was president, the United States provided $236 million.