North Korea fired two short-range missiles on Thursday, South Korea said, an act of defiance that marks the country’s second test launch of weapons in less than a week.

"North Korea launched a short-range missile from the country's northwest Kusong region at 4:29 p.m. and then another short-range missile at 4:49 p.m.," South Korea's Joint Chiefs of Staff said in a statement. Both missiles flew east and over land, with the first one flying 420 kilometers and the second one 270 kilometers across the Korean Peninsula, the Joint Chiefs of Staff said.

The tests follow an increasingly impatient demands for sanction concessions from North Korean leader Kim Jong Un in the wake of his failed February nuclear summit with U.S. President Donald Trump. The Thursday launches came while the U.S.'s top nuclear envoy, Stephen Biegun, was in Seoul to meet with South Korean officials.

On Saturday, Kim supervised the launch of various projectiles, including what non-proliferation experts believed was a short-range ballistic missile. The U.S. and its South Korean allies had played down last weekend's provocation in an attempt to keep it from scuttling talks, even though such a test would represent a violation of United Nation's sanctions.

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While South Korean President Moon Jae-in's office said that he and Trump agreed in a telephone call that the approach was effective, non-proliferation experts said the strategy risked encouraging Kim to conduct more tests. The latest incident bolstered those concerns.

"Since the U.S. response was low key, North Korea appears to think that this level of test would not cause problems and it can continue the tests," said Jina Kim, a research fellow at Korea Institute for Defense Analyses.

North Korea called the Saturday test a reasonable strike drill for its combat readiness, according to a report published on Wednesday in the state-run Korean Central News Agency.

South Korea's military initially said the missiles launched on Thursday came from Sino-ri missile base but later corrected the location to another base 40 kilometers away. The Center for Strategic and International Studies said in January that Sino-ri was one of about 20 undeclared missile operating bases in North Korea, which houses a regiment-sized unit equipped with medium range ballistic missiles.

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