Updated: Aug. 9, 2019, 9:30 p.m.
North Korea has launched more ballistic missiles into the sea off its east coast, its fifth such test in just over two weeks.
The launch Saturday came hours after U.S. President Donald Trump said he received another "beautiful letter" from North Korean leader Kim Jong Un and reiterated he isn't concerned about Pyongyang's missile tests.
South Korean and U.S. intelligence officials say the test appeared to involve a short-range ballistic missile, according to South Korea's presidential Blue House.
The missiles, launched from near the Hamhung area in eastern North Korea, traveled about 400 kilometers and reached a height of 48 kilometers, according to a statement by South Korea's Joint Chiefs of Staff.
The South Korean statement said there is a "high probability" of more North Korean launches in the coming weeks because of ongoing U.S.-South Korean military exercises.
North Korea has regularly launched short-range ballistic missiles into the sea the past two months, an expression of anger at the joint military drills.
US-South Korea military exercises
In his latest letter, Trump says Kim expressed displeasure about the "war games."
"And as you know, I've never liked it either," Trump told reporters Friday. "I've never liked it. I've never been a fan. You know why? I don't like paying for it. We should be reimbursed for it."
The U.S. this week resumed military drills with South Korea, despite Pyongyang's protests.
Trump said he approved the drills because it helped prepare for "a turnover of various areas to South Korea."
"I like that because it should happen," Trump added.
The latest U.S.-South Korean drills are aimed in part at testing South Korea's ability to retake operational control from the U.S. during wartime.
The U.S. has about 28,500 troops in South Korea.
Trump earlier this week announced in a tweet that South Korea had agreed to pay "substantially" more for the U.S. troop presence.
South Korea refuted that allegation, however, saying cost-sharing negotiations with the United States have not yet begun.
Trump has long criticized U.S. allies, including South Korea, Japan and others, for not paying enough for U.S. protection.
U.S.-South Korea military exercises have been scaled back in an effort to support the Trump-Kim diplomacy. But North Korea remains unhappy, warning it may soon resume nuclear and longer-range missile tests.
Since May, North Korea has conducted seven separate launches of short-range ballistic missiles, after having refrained from such tests for a year and a half.
Virtually guarantees missile tests
Trump has said he has "no problem" with the launches, because they are short-range and cannot reach the U.S. But that approach virtually guarantees continued North Korean testing, analysts say.
"Kim knows that he can continue to launch these short-range missiles without consequences. He can continue to provoke, so long as he keeps emitting signals of hope to President Trump directly," said Soo Kim, a former CIA analyst who now works at the U.S.-based Rand Corporation.
"Kim's plodding along faithfully according to plan. He's dialing up the optempo (operational tempo) of his engagement' with President Trump — remaining on our radar through these launches and friendly missives — to put the U.S. in a tighter bind," she adds.
North Korea's launches apparently aim to increase pressure on the U.S. and South Korea ahead of possible talks. They also help North Korea develop its ballistic missile capabilities.
Most of North Korea's recent tests have involved its version of a Russian Iskander ballistic missile, which though short-range, is designed to evade missile defenses and can likely reach all of South Korea.
Despite the repeated tests, Trump on Friday incorrectly said North Korea has not been launching ballistic missiles.
"I say it again: There have been no nuclear tests. The missile tests have all been short-range. No ballistic missile tests. No long-range missiles," Trump said.
That contradicts U.S. and South Korean officials, who view the North Korean weapons as ballistic missiles.
United Nations Security Council resolutions ban North Korea from conducting any ballistic missile activity. North Korea views the resolutions as illegitimate, insisting that every country has the right to test its military capabilities.
Stalled US-North Korea talks
North Korea has said it will give the U.S. until the end of the year to change its approach to the talks, which are stalled yet again. Kim wants the U.S. to relax sanctions and provide security guarantees.
Trump and Kim have met three times since last June, but have failed to make any progress toward dismantling North Korea's nuclear program.
At their first meeting in Singapore, the two agreed to work toward the denuclearization of the Korean peninsula. But neither side can agree on what denuclearization means or how to begin working toward it.
At a second summit in Vietnam in February, Trump and Kim disagreed over how to pair sanctions relief with steps to dismantle North Korea's nuclear program.
Trump and Kim held a third meeting in late June at the demilitarized zone separating the two Koreas, where Kim allegedly agreed to revive working-level talks. Since then, North Korean officials have refused to meet their U.S. counterparts.
On Friday, Trump suggested a fourth meeting could come soon.
"I think we'll have another meeting," Trump said.