The tariff regime was described by the administration as reciprocal response to trade imbalances, but the methodology for calculating tariff rates — dividing trade deficits by import values — was not a recognized economic method and did not reflect actual foreign tariff levels. Economists across the political spectrum warned of consumer price increases, supply chain disruptions, and reduced trade volumes. The tariffs on Chinese goods — reaching 145% cumulatively — effectively ended routine trade in many product categories. Markets fell sharply; the S&P 500 lost approximately 12% in the two trading days following the announcement, its worst two-day drop since 2008. A 90-day pause was announced for most countries (excluding China) after Treasury Secretary Bessent and other officials lobbied Trump.
Trump's second-term Ukraine policy represented a fundamental reversal from the U.S. position that Russian aggression must not be rewarded with territorial gains. The administration froze intelligence sharing and weapons deliveries to Ukraine, sent officials including Steve Witkoff to meet with Putin without Ukrainian representation, and publicly pressured Zelensky to negotiate terms that Ukraine and European allies considered capitulation. The Oval Office meeting on February 28, 2025 became an international incident when Trump and Vice President Vance confronted Zelensky before cameras, accusing him of ingratitude and warning he was 'gambling with World War III.' Zelensky left Washington without a security guarantee or continued military aid.
Trump's January 7, 2025 press conference at Mar-a-Lago was the clearest statement of the annexation posture: asked whether he would rule out military force to take Greenland, he said 'no.' Asked about economic coercion of Canada, he said tariffs were possible. His son Donald Trump Jr. visited Greenland on what was described as a personal trip days before the press conference, raising diplomatic concerns. Denmark's prime minister stated that Greenland was not for sale. Greenland's prime minister stated Greenland's future was for Greenlanders to decide. Panama's president said the canal was and would remain Panamanian. Canada's prime minister described the threats as unacceptable.
NATO's collective defense commitment under Article 5 — that an attack against one member is an attack against all — was the foundational guarantee that had maintained European security for 75 years. Trump's statement that he would encourage Russia to attack members he deemed to be underpaying undermined the credibility of the deterrence that Article 5 provided. NATO allies condemned the statements as dangerous; European leaders described them as a fundamental threat to the alliance's deterrence value. In his second term, Trump continued pressing NATO members with threats of U.S. withdrawal contingent on spending levels, while simultaneously pursuing a Ukraine peace framework that European allies described as favorable to Russia.
Trump had previously threatened to withdraw or defund the WHO in April 2020; in May he made the withdrawal formal. Critics noted that withdrawing from the WHO during a pandemic eliminated U.S. influence over the global response to the same pandemic — including over vaccine development coordination, variant tracking, and equitable distribution programs. The U.S. would lose voting rights, committee seats, and the ability to shape WHO standards and guidelines. Allies and public health experts across the political spectrum criticized the decision. Biden rejoined the WHO within hours of taking office on January 20, 2021.
The Washington Post reported in May 2020 that senior Trump administration officials — including representatives from the Defense and State Departments — discussed at a meeting whether to conduct a nuclear test explosion. The discussions were presented as leverage in arms control negotiations with Russia and China. No test took place, but the public discussion of resuming testing — after a 28-year U.S. moratorium — was treated by arms control experts as a significant destabilization of the global non-proliferation architecture. The Trump administration had already withdrawn from the Intermediate-Range Nuclear Forces Treaty and signaled disinterest in extending New START.
The Open Skies Treaty allows its 35 signatories — including the United States, Russia, and most NATO and former Warsaw Pact nations — to conduct scheduled unarmed reconnaissance flights over each other's territory. The flights collect imagery that member states share, building collective military transparency. Trump administration officials argued Russia had violated the treaty by restricting U.S. flight paths over certain territories. European allies agreed Russia had compliance issues but argued the U.S. should address them within the treaty framework rather than withdraw, and warned that U.S. withdrawal would give Russia an excuse to exit entirely. Russia did subsequently withdraw from the treaty in January 2021, after Trump's withdrawal had set the precedent. The Biden administration reviewed but did not rejoin the treaty due to concerns about congressional opposition.
The Trump administration's Special Envoy Zalmay Khalilzad negotiated the Doha Agreement with Taliban representatives over 18 months. The Afghan government of President Ashraf Ghani was excluded from the negotiations — the Taliban refused to negotiate with the Ghani government and the U.S. accepted this condition. The agreement required the U.S. to release 5,000 Taliban prisoners, including senior military commanders, in exchange for the Taliban releasing 1,000 Afghan security forces. The Taliban made no commitment to halt offensive operations against Afghan forces. The U.S. military assessment was that the Taliban were not fulfilling the agreement's anti-terrorism requirements before the withdrawal was completed.
U.S. Special Representative Zalmay Khalilzad led 18 months of negotiations with Taliban representatives in Doha, Qatar while refusing Taliban demands to include the Afghan government. The Afghan government, which the U.S. had spent nearly two decades and $2 trillion supporting, was effectively presented with the agreement as a fait accompli. Trump personally called Taliban leader Mullah Baradar in a phone call. As part of the deal, the U.S. pressured Afghan President Ghani to release 5,000 Taliban prisoners, including commanders. After Biden inherited the deal, he extended the deadline and withdrew forces in August 2021; the Afghan government collapsed in days.
Mattis had served as Defense Secretary since January 2017. His resignation came after Trump announced — via tweet, without military consultation — that he was withdrawing U.S. troops from Syria, effectively abandoning the Kurdish partners who had done the ground fighting against ISIS. Mattis's resignation letter was unusual in its directness: it stated that he believed Trump had not treated allies with 'respect and seriousness' and had not been 'clear-eyed' about the threats posed by adversaries including Russia and China. Trump, initially describing the departure as planned, later forced Mattis out before the end of his original tenure after the letter's contents became widely circulated.
Khashoggi, a permanent U.S. resident and Washington Post columnist, entered the Saudi consulate in Istanbul to obtain documents for his upcoming marriage. He was killed and his body dismembered by a 15-member Saudi team that included members of MBS's personal security detail. Turkish intelligence recorded audio of the killing and shared it with the CIA. The CIA concluded MBS ordered the operation. Trump's November 2018 statement defending Saudi Arabia cited the CIA assessment as uncertain and emphasized arms sales: '$450 billion of jobs, 450 billion dollars.' Trump resisted congressional pressure for Magnitsky Act sanctions against MBS. The administration characterized MBS's culpability as inconclusive despite CIA findings.
Khashoggi, a permanent U.S. resident and Washington Post contributor, entered the Saudi consulate in Istanbul to obtain marriage documents and was killed by a Saudi hit squad. Turkish intelligence recordings documented the killing. The CIA assessed with high confidence that MBS had ordered it. Trump's response was to prioritize the Saudi relationship over accountability: he repeatedly questioned the CIA's conclusion, cited a $110 billion arms deal with Saudi Arabia, and issued an unprecedented presidential statement that effectively exonerated MBS by saying even if he was responsible, the U.S. would stand by Saudi Arabia. A bipartisan Senate resolution holding MBS responsible was passed; Trump threatened to veto related legislation.
Trump and Putin met privately for approximately two hours with only translators present; there was no U.S. notetaker and Trump reportedly had his interpreter's notes confiscated. At the public press conference, Trump said he didn't 'see any reason why it would be Russia' that interfered in the election — contradicting the unanimous assessment of the U.S. intelligence community. When asked the next day, Trump claimed he had misspoken and meant to say 'wouldn't' instead of 'would.' The statement provoked condemnation from Republican Senate Majority Leader Mitch McConnell, Republican Speaker Paul Ryan, and dozens of Republican members of Congress.
Trump's three meetings with Kim Jong-un (Singapore June 2018, Hanoi February 2019, DMZ June 2019) produced vague joint statements but no binding agreements. North Korea did not submit to inspections, did not provide a declaration of nuclear assets, and did not halt weapons development. Trump unilaterally suspended U.S.-South Korea military exercises after the Singapore summit, calling them 'very expensive war games' and using language Kim had used — a significant concession military commanders opposed. North Korea tested missiles throughout 2019. Talks broke down at Hanoi when the U.S. declined to trade all sanctions for only partial denuclearization.
The JCPOA had halted Iran's path to nuclear weapons by removing sanctions in exchange for verifiable limits on enrichment. The IAEA had certified Iranian compliance in each of its inspections. Trump characterized the deal as 'the worst deal ever made' and the withdrawal as correcting an Obama-era mistake. European allies, who had spent years negotiating the agreement, tried unsuccessfully to persuade Trump to stay in. Following the withdrawal, Iran accelerated its nuclear program, enriched uranium to higher levels than were permitted before the JCPOA, and the U.S. assassination of General Qasem Soleimani in January 2020 brought the two countries to the brink of direct military conflict.
The Section 232 tariffs were challenged immediately as legally dubious — U.S. national security law did not contemplate allies as threats, and Canada, Germany, South Korea, and Japan supply steel and aluminum to U.S. defense contractors. The EU, Canada, and Mexico all retaliated with targeted tariffs on politically sensitive U.S. products (Bourbon, Harley-Davidson motorcycles, orange juice, soybeans). The broader China trade war — separate from the steel tariffs — involved escalating rounds of tariffs reaching 25% on $250 billion in Chinese goods; China retaliated against agricultural products; the U.S. government paid $28 billion in direct payments to American farmers to compensate for lost Chinese export markets.
Trump announced the withdrawal in the Rose Garden, framing it as a defense of American workers against an agreement he claimed was economically harmful. The U.S. had committed under Paris to reduce greenhouse gas emissions 26–28% below 2005 levels by 2025. Trump claimed the accord would cost 2.7 million jobs — a figure taken from a Koch-funded study that most economists disputed. The U.S. was the only major nation to withdraw. The formal withdrawal process took three years under treaty terms; the U.S. officially left the day after the 2020 election. President Biden rejoined on his first day in office.
Trump's first clear signal came in May 2017 at NATO headquarters in Brussels, where he delivered a speech at the unveiling of a 9/11 memorial wall without explicitly affirming Article 5 collective defense — the alliance's core commitment. His aides later said the affirmation had been removed from the speech at Trump's direction. Over the following years, Trump repeatedly demanded NATO allies pay 2% of GDP on defense, threatened withdrawal, and reportedly told European leaders in private that the U.S. might not come to their aid. In February 2024, during the 2024 campaign, Trump stated publicly that he would 'encourage' Russia to attack NATO members who he thought hadn't paid enough.
The TPP was designed explicitly to be a counterweight to Chinese economic influence in the Asia-Pacific region — establishing labor standards, intellectual property rules, and trade norms that reflected democratic values rather than Chinese state capitalism. Trump's withdrawal handed China the diplomatic and economic initiative in the region it had been seeking. The 11 remaining nations completed the CPTPP without the U.S.; China has since established its own trade framework covering much of the same region.