U.S. defense officials have claimed that recently North Korea conducted another ballistic missile engine test.
According to officials, the engine trial which was carried out on Friday was the third such test in recent weeks using similar technology.
CNN quoted one official as saying that engine technology could possibly be used in a eventual intercontinental ballistic missile.
In a reaction indicating show of force following the increased provocations from North Korea, the US Marines have deployed F-35Bs to South Korea for the first time as part of an exercise that began Friday.
"This is the first time we have operated the F-35B in the Republic of Korea," said Pentagon spokesman US Navy Capt. Jeff Davis.
North Korea had last week conducted a ground jet test of a newly developed high-thrust missile engine at its Tongchang-ri rocket launch station.
Although North Korea has never flight-tested an intercontinental ballistic missile, it has recently demonstrated significant progress in its missile programs with new engines that could potentially deliver a nuclear warhead as far away as the United States.
U.S. Secretary of State Rex Tillerson had said earlier during his visit to South East Asia that Washington would consider military action against North Korea if it was provoked.