On November 29, 2017, North Korea test-fired a ballistic missile that North Korean officials claim can deliver a nuclear warhead to any city in the United States.Footnote 1 According to North Korea's leader Kim Jong Un, the missile launch “finally realised” the nation's ambition “of completing the state nuclear force, the cause of building a rocket power.”Footnote 2 At the same time, U.S. officials have reiterated that “[t]he United States does not accept a nuclear North Korea.”Footnote 3 As a result, North Korea's fast-expanding nuclear weapons program has exacerbated the already fraught relations between the two countries.
During the latter half of 2017, the two nations engaged in an escalating tit-for-tat exchange of military threats. On August 8, President Trump told reporters: “North Korea best not make any more threats to the United States. They will be met with fire and fury like the world has never seen.”Footnote 4 The following day, North Korea revealed a strike plan to launch nuclear weapons at the American territory of Guam.Footnote 5 In September, during his address to the United Nations General Assembly, Trump said:
No one has shown more contempt for other nations and for the well-being of their own people than the depraved regime in North Korea. … [N]ow North Korea's reckless pursuit of nuclear weapons and ballistic missiles threatens the entire world with unthinkable loss of human life. … The United States has great strength and patience, but if it is forced to defend itself or its allies, we will have no choice but to totally destroy North Korea. Rocket Man is on a suicide mission for himself and for his regime. … It is time for North Korea to realize that the denuclearization is its only acceptable future.Footnote 6
In response, North Korea's Foreign Minister called Trump's comments “a declaration of war” and claimed North Korea has the right to shoot down American military planes operating outside North Korea's airspace.Footnote 7
As suggested by Trump's UN remarks above, the two nations’ leaders have also exchanged a series of personal insults and rebukes. Following Trump's remarks at the United Nations, Kim Jong Un called Trump “a mentally deranged U.S. dotard.”Footnote 8 Trump has repeatedly and disparagingly referred to Kim Jong Un as “Little Rocket Man.”Footnote 9 Though the threats and insults have garnered substantial media coverage, little attention has been paid to whether they constitute an unlawful threat of force under Article 2(4) of the UN Charter.Footnote 10
Several American allies have expressed concern at this brinkmanship. In August, New Zealand's Prime Minister Bill English called Trump's threats “not helpful when the situation is so tense.”Footnote 11 The German Foreign Ministry tweeted “[s]abre-rattling won't help,” and “call[ed] on all parties for moderation.”Footnote 12 And in South Korea, newly-elected President Moon Jae-in said: “Only the Republic of Korea can make the decision for military action on the Korean Peninsula. Without the consent of the Republic of Korea, no country can determine to take military action.”Footnote 13
Though neither side has gone beyond rhetorical threats, the Trump administration has made clear that “all options are on the table” with respect to North Korea.Footnote 14 The possibility of the United States launching a “first strike” raises several contested legal issues, including (1) whether, given North Korea's rhetoric and nuclear capabilities, such a strike would be in self-defense under the familiar Caroline test; (2) relatedly, whether such a strike would put the United States in breach of Article 2(4) of the UN Charter; and (3) to what extent the president has constitutional authority to order the use of force against North Korea in the absence of congressional authorization.Footnote 15
More generally, the Trump administration has articulated a policy of “strategic accountability” aimed at “the complete, verifiable and irreversible denuclearization of the Korean Peninsula.”Footnote 16 According to Secretary of State Rex Tillerson and Secretary of Defense James Mattis, the policy entails working “with the support of the international community” to apply “diplomatic and economic pressure on North Korea.”Footnote 17 The policy is intended to replace what they describe as the earlier “failed policy of ‘strategic patience.’”Footnote 18
The Trump administration has achieved some success in mobilizing the international community with respect to North Korea. On August 5, 2017, the UN Security Council unanimously adopted a resolution strengthening economic sanctions on North Korea.Footnote 19 Among other things, Resolution 2371 targets specific sectors of the North Korean economy—prohibiting the sale of coal, iron, iron ore, seafood, lead, and lead ore to other countries.Footnote 20 According to press reports, “China's Commerce Ministry announced it would enforce the new rules passed by the United Nations Security Council as punishment for the North's nuclear and missile tests” following requests by the Trump administration.Footnote 21
After a North Korean nuclear test on September 2, the Security Council further tightened sanctions on September 11.Footnote 22 The Council voted unanimously in Resolution 2375 to impose what the U.S. Ambassador to the United Nations Nikki Haley called “massive sanctions” on North KoreaFootnote 23 —including a ban on the sale of liquefied natural gas to the regime, a cap on oil exports to the country, and new sanctions on the country's textile industry.Footnote 24 On December 22, the Security Council went further and unanimously adopted new, tougher sanctions on the North Korean regime.Footnote 25 Resolution 2397 largely prohibits the direct or indirect supply of crude oil, refined petroleum products, and other raw materials to North Korea.Footnote 26 Further, the Security Council directed states to inspect and seize ships that these states have reasonable grounds to believe are involved in transporting items prohibited by United Nations sanctions.Footnote 27 Finally, Resolution 2397 instructs states to repatriate North Korean nationals earning income abroad within the next two years.Footnote 28 North Korea called the most recent round of sanctions an “act of war.”Footnote 29
The United States has also rallied nations to isolate North Korea diplomatically. In early October, the United States “secured a commitment from Sudan to stop buying arms from North Korea” as part of the process of lifting American sanctions on Khartoum.Footnote 30 Also in October, Italy became the fifth country—after Spain, Mexico, Peru, and Kuwait—to expel the North Korean ambassador this year.Footnote 31 Reports indicate that the Trump Administration has been “vigorously lobbying” governments to cut diplomatic relations with North Korea.Footnote 32 Indeed, the Trump administration allegedly issued a directive instructing diplomats to “bring up North Korea in virtually every conversation with foreign interlocutors and urge them to sever all ties with Pyongyang.”Footnote 33
In addition to mobilizing the international community, the United States has also taken unilateral action to increase economic and diplomatic pressure on North Korea. Following North Korea's test of a ballistic missile that overflew Japan on September 14, Trump issued an executive order on September 20 imposing additional sanctions on North Korea designed to cut the regime off from the international financial system.Footnote 34 The order authorizes the U.S. Treasury secretary to “prohibit the opening and prohibit or impose strict conditions on the maintenance of correspondent accounts or payable-through accounts in the United States” as well as to “block all property and interests in property that are in the United States” or that will “come within the United States” of any financial institution that is determined to have “knowingly conducted or facilitated any significant transaction in connection with trade with North Korea.”Footnote 35 The new sanctions enable the United States, according to Treasury Secretary Steven Mnuchin, “to freeze or block any transactions, with any financial institution, anywhere in the world that facilitates any transactions” with North Korea or North Korean officials.Footnote 36
The Trump administration has also taken other, more symbolic action. Though almost no North Korean nationals travel to the United States,Footnote 37 Trump included North Korea in the third iteration of his travel ban, indefinitely suspending “entry into the United States of nationals of North Korea as immigrants and nonimmigrants.”Footnote 38 And on November 20, 2017, the Trump administration redesignated North Korea as a state sponsor of terrorism.Footnote 39 Though the practical effects of the designation are limited—state sponsors of terror are subject to a “range of sanctions,” such as a ban on American arms-related sales and exports, that are largely redundant with already existing sanctions on North KoreaFootnote 40 —Trump claimed the “designation will impose further sanctions and penalties on North Korea and related persons, and supports our maximum pressure campaign to isolate the murderous regime … .”Footnote 41
Even as the United States has taken steps to isolate North Korea economically and diplomatically, the U.S. State Department has kept lines of communication open with North Korean leadership. In late September, Tillerson revealed that the two nations were in direct communication.Footnote 42 On December 12, 2017, Tillerson asserted that the United States is “ready to talk anytime North Korea would like to talk.”Footnote 43 Although he initially suggested the United States would be willing to meet “without precondition[s],”Footnote 44 Tillerson struck a tougher tone a few days later, insisting “a sustained cessation of North Korea's threatening behavior must occur before talks can begin. North Korea must earn its way back to the table.”Footnote 45
The White House has expressed greater skepticism about the prospects of negotiating with Pyongyang. Referring to the Secretary of State's remarks in late September, Trump tweeted that Tillerson “is wasting his time trying to negotiate with Little Rocket Man.”Footnote 46 And in December, the White House issued a statement distancing itself from Tillerson's initial offer to meet with North Korea “without precondition,” saying: “The President's views on North Korea have not changed.”Footnote 47
