South Korean and US Marines have kicked off two weeks of joint drills – days after Seoul and Washington agreed to suspend a major aerial exercise in December, and just before the US Secretary of State is expected to speak to North Korean counterparts.

The drills are taking place days after North Korea, apparently frustrated with lack of progress in its talks with the United States, threatened to resume nuclear activities.

Though the exercises are small in scale – just 500 troops, less than a full battalion, are deploying, according to South Korean media – they are notable as no other South Korea-US Marine drills have taken place since May.

Flexing some muscle

The drills are underway near the city of Pohang, a key base for South Korean Marines, on South Korea’s southeast coast. There, Korean Marines are joined by counterparts from the US 3rd Marine Expeditionary Force, or 3rd MEF, based in Okinawa, Japan.

Seoul and Washington have refrained from major war games since the June summit in Singapore between North Korean leader Kim Jong Un and US President Donald Trump, in order to mollify Pyongyang.

And just last week, South Korean Defense Minister Jeong Kyeong-doo said, following his annual Security Consultative Meeting with US Defense Secretary James Mattis in Washington last week, that the two had agreed not to conduct annual Vigilant Ace air drills. After the Key Resolve and Foal Eagle spring exercises, aerial drills, including Vigilant Ace, tend to be the highest profile on the allies’ calendar.

Moreover, Jeong said working-level meetings would decide the fate of next year’s spring drills by December 1.

North Korea frequently complains about allied drills, claiming they are rehearsals for an invasion. It was due to Pyongyang’s sensitivities – and what he called their high expense – that Trump agreed to indefinitely halt major war games this spring. The current Marine drills are minor in scale.

Send in the Marines

However, Marine units, such as those exercising today, are particularly sensitive for Pyongyang.

Korea is a peninsula and highly vulnerable to amphibious operations, especially those carried out by the US Navy, the world’s largest battle fleet. In 1950 the famous Inchon landing, conducted by US Marines, temporarily turned the tide of war against invading North Korean troops. Today, the powerful  3rd MEF in Okinawa is a key reinforcement and maneuver element that would deploy should a future conflict break out in Korea.

Marine units are also among the most highly trained and aggressive troops in both the South Korean and US militaries. In 2010, North Korea unleashed an artillery barrage upon the frontline island of Yeonpyong in the Yellow Sea after South Korean Marines there conducted a firing drill – albeit, aimed out into open water, rather than toward the North Korean coast.

Pyongyang signals frustration

Last Friday, in a statement released by its Foreign Ministry, Pyongyang threatened to return to its “byungjin” policy line –  its policy of engaging in dual track economic and nuclear arms development – if the US does not ease sanctions against it. The statement also said, “improvement of relations and sanctions is incompatible.”

North Korea has refrained from testing any atomic devices or missiles this year and has blown up at least parts of its nuclear test site at Punggye-ri in a goodwill gesture aimed at Washington. However, expert and satellite analyses suggest that work continues at North Korean nuclear and weapons facilities.

“What was the evidence that they ever stopped? I have not seen any party guidance that the byungjin line is overturned,” said Daniel Pinkston, an international relations expert with Troy University, suggesting that the regime puts out different messages for internal and external audiences. “You can do a lot without nuclear explosion tests and missile flight tests.”

Pyongyang’s Foreign Ministry statement seems to be a signaling frustration that North Korea-US relations are stuck in a rut.

Since the June Singapore summit, in meetings largely – but not exclusively – held between Kim Yong Chol, a former espionage general who has emerged as a close aide to Kim Yong Un over the course of the year, and US Secretary of State Mike Pompeo, little progress has been made on three key issues.

While North Korea seeks sanctions relief and a peace treaty to end the Korean War, the US side is almost entirely focused on denuclearization.

Pompeo is scheduled to talk with un-named North Korean officials later this week. Denuclearization, and the setting up of a second summit between the North Korean and US leaders in early 2019, are expected to be the key agenda items.

Asked whether today’s Marine drills are a pressure tactic being applied ahead of the meeting, Troy University’s Pinkston said: “We may be trying to read too much into it. People have to train and maintain efficiency, it’s not a big deal.”