North Korea has been silent on the US deployments of an aircraft carrier and a strategic bomber in South Korea this month. Some observers say Pyongyang may be focusing on its planned launch of a military reconnaissance satellite.

Earlier this month, the United States sent the nuclear-powered aircraft carrier Ronald Reagan to a port in South Korea and landed a nuclear-capable B-52 bomber. It also conducted joint drills with South Korea and Japan.

North Korea reacted sharply to these moves, with its state-run news agency affirming that US strategic assets are its "first targets of destruction."

But unlike before, North Korea has not launched any ballistic missiles in response to these recent developments.

From September to October last year, when the Ronald Reagan sailed near the Korean Peninsula, Pyongyang fired ballistic missiles seven times as a warning during a training exercise of its tactical nuclear operations unit.

The North also launched short-range ballistic missiles in response to the deployment of the US nuclear-powered flattop Nimitz in March.

It also set off short-range ballistic missiles each time a B-52 bomber landed in the South in December last year and when B-1 bombers arrived in February and August this year.

North Korea has announced plans for a third attempt to launch a military reconnaissance satellite this month, following its failed tries in May and August.

Some South Korean media outlets speculate that Pyongyang may be preoccupied with preparations for the upcoming satellite launch, potentially explaining the lack of response to the US.