President Moon Jae-in on Sunday started an eight-day tour of Finland, Norway and Sweden. It is his first trip to the northern European nations since he took office more than two years ago.

Summit diplomacy with any country is important, and as the head of state of a country that has maintained friendly and cooperative relations with the three countries, Moon’s task is to use his trip to forge closer ties with them.

That doesn’t seem so difficult, compared with other foreign policy and diplomatic challenges the president has to tackle upon his return home.

One tough diplomatic challenge for the Moon government concerns the escalating tension between the US and China. It is apparent that what started as a trade war is developing into a hegemonic battle between the world’s two superpowers.

The tariff war between the US and China has spread to the technology front, with the US side, citing security reasons, prodding its allies to ban fifth-generation wireless network equipment from the Chinese tech giant Huawei.

China is not sitting idle, threatening retaliation and forming its own coalition. Last week, China and Russia signed an agreement in St. Petersburg to pave the way for Russia to use Huawei’s 5G technology. Visiting Chinese President Xi Jinping and Russian President Vladimir Putin applauded as their representatives signed the deal, apparently to send a message to the US.

South Korea cannot avoid being drawn into the growing US-China clashes, which some even describe as a new cold war. Specifically, both the US and China are pressuring the Seoul government to take sides on the use of Huawei equipment.

For now, US Ambassador Harry Harris seems to be acting as Washington’s messenger in the US campaign against Huawei.

Harris, a former US Navy admiral, expressed concern over the security of the Huawei 5G system twice last week. He did not directly call on the Korean government or Korean companies to ban Huawei equipment, but his meaning was clear.

“We are naturally concerned about the security implications of how the 5G network will be instantiated across Korea,” Harris said at a security forum in Seoul on Friday.

“But as allies and friends, I am confident that we will work through all of these issues together. We have work to do and we will work on these and other issues together,” he said.

Two days earlier, the US ambassador said in a technology forum that “decisions made today regarding 5G networks will have national security implications for decades.” He added that Korean firms should choose a “trustworthy” system provider.

The Chinese ambassador to South Korea has yet to speak publicly on the issue, but a senior Chinese Foreign Ministry official was quoted as telling Korean reporters in Beijing last week that the Seoul government should make the “right judgment.”

It is not hard to imagine that as the US-China battle intensifies, Korea will face increasing pressure from both sides. Troublingly, the Seoul government seems far too complacent.

A senior presidential official played down the risks to Korea from the US-China war over Huawei equipment. He noted that military and other security-related communications systems are separate from the Chinese-made equipment used in the 5G infrastructure.

Government officials also said Huawei equipment made up only 10 percent of the 5G network in Korea, as compared with 40 percent in the EU and more than 70 percent in Indonesia. Some even said it should be up to individual companies to decide whether to use Huawei equipment.

These comments show that the Moon government lacks a strategy -- when the US and China officially ask it to stand on one side or the other, it has no idea what stance it should take. It brings to mind the government of former President Park Geun-hye and the way it mishandled the decision to bring a US missile-defense system into Korea.

All in all, the US-China rivalry is expanding its battlefronts and is putting Korean diplomacy to another serious test. The series of summit talks to be held late this month on the sidelines of the G20 meeting in Japan and US President Donald Trump’s upcoming visit to Korea will shed some light on how Moon will cope with the test.