North Korea said on Thursday it successfully launched ballistic missiles from a train for the first time and was continuing to bolster its defences, after the two Koreas test-fired missiles hours apart in dueling displays of military might. Wednesday’s launches underscored a return of the tensions between the rivals amid a prolonged stalemate in U.S.-led talks aimed at stripping North Korea of its nuclear weapons programme. Pyongyang’s official Korean Central News Agency said the missiles were launched during a drill of a “railway-borne missile regiment” that transported the weapons system along rail tracks in the country’s mountainous central region and accurately struck a sea target 800 kilometers (500 miles) away. State media showed what appeared to be two different missiles streaking up from rail-car launchers engulfed in orange flames along tracks surrounded by dense forest. A rail-based ballistic system reflects North Korea’s efforts to diversify its launch options, which now includes various vehicles and ground launch pads and may eventually include submarines. Firing a missile from a train could add mobility, but some experts say North Korea’s simple rail networks running through its relatively small territory would be quickly destroyed by enemies during a crisis.