South Korea's inclusion in the United States' list of countries that could have a 53 percent tariff levied on their steel exports is a "red light" in economic relations between the two countries, the main opposition party said Monday.

Imposition of the hefty tariff on steel imports from 12 countries was one of three suggestions that the US Commerce Department made to President Donald Trump to protect the local industry. South Korea was the only US ally included in the list.

"At a time when we cannot foresee how North Korea-US relations will develop after the PyeongChang Olympics, a red light has come on in the economy," Rep. Kim Sung-tae, floor leader of the Liberty Korea Party said during a party meeting.

Kim pointed out that the US included South Korea in what he called the "sanctions list" while excluding such traditional friends as Canada, Japan and Germany, even though Canada is the biggest steel exporter to the US.

"We have to make sure that signs of cracks in the security and economic alliance between South Korea and the US won't become larger if the security situation on the Korean Peninsula over the North Korean nuclear issue heads toward a crisis," Kim said.

The LKP has warned of possible strains in South Korea's relations with the US as Seoul seeks rapprochement with North Korea at a time when Washington has been seeking to put maximum pressure on the communist regime for its nuclear missile program.

In recent weeks, inter-Korean relations have warmed rapidly as North Korean leader Kim Jong-un has stepped up his peace offensive toward the South, sending his only sister to the South as part of a high-level delegation to the Olympics and inviting Moon to visit the North.

Moon said in response he hopes the right conditions will be created so that the proposed visit can take place. The remark was seen as meaning that there should first be progress on efforts to resolve the North Korean nuclear standoff, such as talks between the United Sates and the North, before an inter-Korean summit takes place.

Conservative opposition parties and other critics have voiced concern that the South is playing into the North's hands and that the communist regime is using the charm offensive to undermine international sanctions against it.(Yonhap)