By Ju-min Park and Jack Kim

SEOUL, May 30 (Reuters) - North Korean leader Kim Jong Un supervised the test of a new ballistic missile controlled by a precision guidance system and ordered the development of more powerful strategic weapons, the North's official KCNA news agency reported on Tuesday.

The missile launched on Monday was equipped with an advanced automated pre-launch sequence compared with previous versions of the "Hwasong" rockets, North Korea's name for its Scud-class missiles, KCNA said. That indicated the North had launched a modified Scud-class missile, as South Korea's military has said.

The North's test launch of a short-range ballistic missile landed in the sea off its east coast and was the latest in a fast-paced series of missile tests defying international pressure and threats of more sanctions.

Kim said the reclusive state would develop more powerful weapons in multiple phases in accordance with its timetable to defend North Korea against the United States.

"He expressed the conviction that it would make a greater leap forward in this spirit to send a bigger 'gift package' to the Yankees" in retaliation for American military provocation, KCNA quoted Kim as saying.

South Korea said it had conducted a joint drill with a U.S. supersonic B-1B Lancer bomber on Monday. North Korea's state media earlier accused the United States of staging a drill to practise dropping nuclear bombs on the Korean peninsula.

The U.S. Navy said its aircraft carrier strike group, led by the USS Carl Vinson, also planned a drill with another U.S. nuclear carrier, the USS Ronald Reagan, in waters near the Korean peninsula.

A U.S. Navy spokesman in South Korea did not give specific timing for the strike group's planned drill.

North Korea calls such drills a preparation for war.

Monday's launch followed two successful tests of medium-to-long-range missiles in as many weeks by the North, which has been conducting such tests at an unprecedented pace in an effort to develop an intercontinental ballistic missile (ICBM) capable of hitting the mainland United States.

Such launches, and two nuclear tests since January 2016, have been conducted in defiance of U.S. pressure, U.N. resolutions and the threat of more sanctions.

They also pose one of the greatest security challenges for U.S. President Donald Trump, who portrayed the latest missile test as an affront to China.

"North Korea has shown great disrespect for their neighbor, China, by shooting off yet another ballistic missile ... but China is trying hard!" Trump said on Twitter.