North Korea fired a pair of ballistic missiles off its east coast today, South Korea's military said, ratcheting up regional tension just days after testing a cruise missile that is believed to have nuclear capabilities.

The launches came amid a flurry of activity on the peninsula, including high-level diplomatic talks and South Korea's testing of a newly developed submarine-launched ballistic missile of its own.

North Korea has been steadily developing its weapons systems amid a standoff over talks aimed at dismantling its nuclear and ballistic missile arsenals in return for US sanctions relief. The negotiations, initiated between former...