North Korea's missile program is progressing faster than expected, a South Korean minister said Tuesday, hours after the U.N. Security Council demanded the North halt all nuclear and ballistic missile tests and condemned Sunday's test-launch.

The reclusive North, which has defied all calls to rein in its weapons programs, even from its lone major ally, China, has been working on a missile, mounted with a nuclear warhead, capable of striking the U.S. mainland.

U.S. President Donald Trump's administration has called for an immediate halt to Pyongyang's nuclear and missile programs and has warned that the "era of strategic patience" with North Korea under previous presidents was at an end.