(Bloomberg) -- North Korea may be looking at test firing its first intercontinental ballistic missile in more than four years as the strongest move it could soon make to ratchet up tensions with the U.S., a South Korean lawmaker said after a briefing by the country’s spy agency.

“The most probable card for provocation that North Korea could play would be firing an ICBM,” opposition lawmaker Ha Tae-keung of the told reporters Friday after being briefed by National Intelligence Security officials in a parliamentary committee. NIS officials weren’t immediately available for comment.

North Korean leader Kim Jong Un this week indicated he may end a more than four-year-old freeze on major weapons tests. Forcing a crisis with Washington may be 38-year-old Kim’s best chance to break a diplomatic stalemate that has kept crippling sanctions in place and left the economy smaller than when he took power a decade ago.

The last time Kim’s regime tested a nuclear weapon as well as an ICBM to deliver a warhead to the U.S. mainland was in 2017. Kim then started a moratorium on tests of atomic bombs and long-range missiles to pave the way for unprecedented talks with former President Donald Trump. 

Despite three face-to-face meetings, talks between Kim and Trump resulted in no tangible steps to wind down North Korea’s nuclear arsenal. As the discussions sputtered, Kim’s state was busy adding to its stockpile of fissile material and developing new missile systems to deliver nuclear weapons to U.S. allies in Asia.

While North Korea has refrained from ICBM launches, it has conducted tests of new missile systems designed to evade U.S.-operated interceptors with ranges to strike South Korea and Japan, which host the bulk of American troops in the region. The absence of tests that directly threaten the U.S. has made it easier for President Joe Biden to avoid another confrontation with Kim, like when Trump threatened to unleash “fire and fury” against the regime.

North Korea has already in January conducted the most ballistic missiles tests in a month since 2019, while promising a “stronger and certain reaction” to a fresh round of U.S. sanctions against people accused of securing materials for the regime’s weapons program. In the past week, North Korea resumed rail-borne trade with its biggest benefactor China, in another sign it needs outside help. 

South Korea’s spy agency said 20 train cars a day have been transporting food, building materials and medical supplies from China to North Korea since Monday, Ha told reporters. 

Cheon Seong-whun, a former security strategy secretary at South Korea’s presidential Blue House said the latest moves indicate a heightening of tensions in the “vicious cycle” of provocations.

He sees an ICBM launch as a strong possibility as well as a possible launch of a rocket to deliver a satellite. This would serve two purposes in showing that North Korea can match South Korea’s space program after it launched a new rocket in October and help Pyongyang advance its technology for an ICBM.

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