The United States flew two supersonic bombers over the Korean Peninsula on Tuesday in a show of force against North Korea, South Korean officials said.

The U.S. often sends powerful warplanes in times of heightened animosities with North Korea, and flew B-1B bombers several times this year as the North conducted a series of banned ballistic missile tests.

Tuesday’s flights by B-1Bs came shortly after the death of a U.S. college student who was recently released by North Korea in a coma following more than 17 months of captivity.