The U.S. is trying to send North Korea a message.
The bombers were only doing practice drills, but U.S. military officials said the trip was made in direct response to North Korea's actions.
North Korea has been warned not to push its nuclear and missile programs. Still, the country has conducted at least 11 test launches since the beginning of 2017.
U.S. President Donald Trump told reporters he's considering some "pretty severe things" to respond to the North's provocative ICBM test launch.
After 10 hours of drills, the bombers returned to their base in Guam.