SEOUL, South Korea -- North Korea fired a projectile into waters off its eastern coast Sunday, a day after launching three short-range missiles in the same area, officials said.
North Korea routinely test-launches short-range missiles. But the latest launches came during a period of tentative diplomacy aimed at easing recent tension, including near-daily threats by North Korea to attack South Korea and the United States earlier this year.
The fourth launch occurred Sunday afternoon, according to officials at Seoul's Defense Ministry and Joint Chiefs of Staff. The officials, who spoke on condition of anonymity, refused to say whether it was a missile or artillery round.
On Saturday, North Korea fired two short-range missiles in the morning and another in the afternoon.
The United States responded by saying threats or provocations would only further deepen North Korea's international isolation, while South Korea called the launches a provocation.
The North has a variety of missiles but Seoul and Washington don't believe the country has mastered the technology needed to manufacture nuclear warheads small and light enough to be placed on a missile capable of reaching the United States.
South Korea's Defense Ministry said Sunday it has deployed dozens of Israeli-made precision guided missiles on front-line islands near the disputed western sea boundary as part of an arms buildup begun after a North Korean artillery strike on one of the islands in 2010 killed four South Koreans.