North Korea launched two suspected ballistic missiles into the Sea of Japan on Thursday, the sixth round of weapons launches this month, according to South Korea's military.

The Joint Chiefs of Staff of South Korea said the weapons, which were likely short-range, were launched from an eastern coastal area, but it didn't specify how far they flew.

N. Korea, US tension

North Korea has recently increased its testing activity in an apparent effort to put pressure on the Biden administration amid long-stalled nuclear talks. The renewed pressure comes as the pandemic shook the North's economy, which had already been battered by crippling US-led sanctions over its nuclear weapons program.

It issued a veiled threat last week to resume testing of nuclear explosives and long-range missiles aimed at the US, which leader Kim Jong-Un suspended in 2018 while engaging in diplomacy with the US.

Kim's high-stakes talks with former President Donald Trump fell through in 2019 due to disagreements over sanctions relief and denuclearization.

According to some experts, North Korea's weapons demonstrations could skyrocket following the Winter Olympics, which begin on February 4 in China. They believe Pyongyang's leadership believes it can use a dramatic provocation to sway the Biden administration.

The Biden administration has allegedly offered open-ended talks but has shown no actual willingness to ease sanctions, preconditioning that Kim makes concessions and takes concrete steps to abandon the nuclear weapons.

N. Korea increases testing activities

Since last fall, the North has increased its testing activity, demonstrating various missiles and delivery systems that appear to be designed to overwhelm regional missile defense systems.

Experts believe Kim is putting more pressure on rivals, Washington and Seoul, to accept it as a nuclear power in the hopes of avoiding economic sanctions and converting the diplomacy with Washington into mutual arms-reduction talks.

The launch on Thursday came two days after the South Korean military discovered the North flight-testing two suspected cruise missiles in an unspecified inland area. 

The North also tested two different types of short-range ballistic missiles developed since 2019 that are designed to be maneuverable and fly at low altitudes, potentially improving their chances of evading and defeating missile defense systems, according to experts.