The country's faced U.N. sanctions since 2006, and it's unclear if the latest measures will slow down its nuclear program.
President Trump announced his plan to visit five Asian countries to increase international support to rein in North Korea.
The funds will be distributed via United Nations agencies to help North Korean children and pregnant women.
Spain said its ambassador from North Korea must leave soon. Mexico, Kuwait and Peru recently did something similar.
U.S. officials said a military option with North Korea might be necessary but that it's not what they would prefer to do.
Four countries are now under differing levels of visa restrictions.
The United Nations Security Council voted Monday to impose a fresh round of sanctions on North Korea over its latest nuclear test.
The U.S. reportedly wants to cut off oil and natural gas exports to North Korea, but China and Russia could veto that plan.
China said Trump's latest idea to deal with North Korea's aggression was both "unacceptable" and "unfair."
U.S. President Donald Trump warned in a brief statement Tuesday that "all options are on the table" when it comes to Pyongyang.
State-released photos show North Korea is developing solid-fuel missiles, which are harder to defend against.
The U.S. is imposing new sanctions on Chinese and Russian companies and on individuals accused of helping North Korea.