The US sent two Air Force B-1 bombers over the Korean peninsula on Monday, just days after North Korea conducted another ballistic missile launch.
In 2017 alone, North Korea has carried out 8 missile launches - 5 successfully and 3 unsuccessfully. Still, this is far fewer than the last three years. North Korea attempted 24 missile launches in 2016, 15 in 2015 and 19 in 2014.
The graphic below shows the number of missile launches conducted by Pyongyang since 1984:
Mike Nudelman/Business Insider