This year, with a steady stream of battlefield imagery and security concerns dominating the headlines, it has become easy to forget how rare this level of global tension once felt.
While 2025 did not drag the world to the brink of a world war, it delivered some tense moments that made many pause and ask how stable the global order really is.
Highlights
- Russia ended its self-imposed missile moratorium in August, citing security concerns and U.S. missile deployments in Europe.
- Poland invoked NATO's Article 4 after 19 Russian drones entered its airspace, prompting a reinforced NATO defense posture.
- In October, Trump ordered the Pentagon to resume nuclear testing, breaking a moratorium held since 1992, citing rival test programs.
From nuclear warnings to close military encounters and growing standoffs between major powers, the past 12 months were filled with situations that could, if mishandled, have spiralled far beyond their original borders.
Again and again, global powers pushed, tested and warned each other without fully crossing the line.
These were not apocalyptic moments, but they were dangerous ones—ones that, if misjudged, could have changed the course of history.
Outlined below are some of the moments that best captured that fragile balance.
Russia abandons its self-imposed missile moratorium
Russia announced in early August that it would no longer consider itself bound by a self-imposed moratorium on the deployment of intermediate-range missiles—the voluntary restraint Moscow had observed since the collapse of the 1987 Intermediate-range Nuclear Forces (INF) Treaty.
The declaration ended a period in which Russia said it would not station or deploy ground-launched missiles in the 500–5,500 km range capable of carrying nuclear warheads.
Russian officials framed the decision as a response to what they described as a deteriorating security environment.
Russian President Vladimir Putin. Image credits: Contributor/Getty Images
In a statement, the Foreign Ministry linked the move to the U.S. and allies preparing to deploy intermediate long-range weapons to Europe, citing a plan for the U.S. to deploy Typhoon and Dark Eagle missiles in Germany from 2026.
“Russia no longer has any limitations, Russia no longer considers itself to be constrained by anything,” Kremlin spokesman Dmitry Peskov told reporters.
“Therefore, Russia believes it has the right to take respective steps if necessary.”
In a statement, the Foreign Ministry added, “Decisions on specific parameters of response measures will be made by the leadership of the Russian Federation based on an interdepartmental analysis of the scale of deployment of American and other Western land-based intermediate-range missiles, as well as the development of the overall situation in the area of international security and strategic stability.”
The announcement came after U.S. President Donald Trump said he had ordered two nuclear-capable submarines to be strategically re-positioned closer to Russia.
Trump moved submarines closer to Russia. Image credits: Alex Wong/Getty Images
It followed threats made by former Russian president Dmitry Medvedev, who had said Trump’s push for Russia to agree to a ceasefire deal in Ukraine and the potential use of sanctions was “a step towards war.”
Medvedev commented on the Foreign Ministry’s statement on X, describing the move as “the result of NATO countries’ anti-Russian policy.”
“This is a new reality all our opponents will have to reckon with,” he said. “Expect further steps.”
Heightened NATO–Russia tensions after airspace incursions
In September, Poland invoked Article 4 of the North Atlantic Treaty Organization (NATO) after about 19 Russian drones entered its airspace from Belarus.
Polish and NATO forces responded—shooting down several drones—and the breach prompted emergency consultations among NATO allies.
Polish Prime Minister Donald Tusk said the country was the closest it has been to open conflict since World War II.
Polish Prime Minister Donald Tusk. Image credits: Halil Sagirkaya/Anadolu via Getty Images
Russia denied targeting Poland and said it was conducting a mass strike against military targets in Ukraine, with four of those drones shot down by Polish and NATO aircraft.
In its aftermath, NATO launched a reinforced air-defence posture along its eastern flank under Operation Eastern Sentry.
“Eastern Sentry and this new approach will deliver even more focused and flexible deterrence and defence where and when needed to protect our people and deter against further reckless and dangerous acts like what occurred earlier this week,” General Alexus G. Grynkewich, Supreme Allied Commander Europe, said.
NATO Secretary General Mark Rutte told reporters at a press conference that the violation was not an isolated incident and said allies “denounced Russia’s reckless behavior.”
While stray missiles and drones have landed in NATO states before, the incident marked the first confirmed shoot-down of Russian drones inside allied territory.
NATO launched Operation Eastern Sentry. Image credits: Mateusz Slodkowski/Getty Images
Article 4 allows NATO member nations to call for an urgent consultation when “the territorial integrity, political independence or security of any of the parties is threatened.”
Invoking Article 4 does not automatically trigger collective defense measures but grants consultations whenever a member believes its territorial integrity, political independence or security is threatened.
If the alliance had determined that the incursions constituted a deliberate attack on NATO territory, it could have led to invoking Article 5—the treaty’s mutual defense clause, which considers an attack on one as an attack on all.
It has only been triggered once in NATO’s history, in response to the 9/11 terror attack in the U.S.
Trump Orders Pentagon to immediately begin testing nuclear weapons
At the end of October, President Trump ordered the Pentagon to immediately resume testing nuclear weapons for the first time since 1992.
“Because of other countries’ testing programs, I have instructed the Department of War to start testing our Nuclear Weapons on an equal basis,” he wrote on Truth Social.
“That process will begin immediately.”
Trump ordered the Pentagon to test nuclear weapons. Image credits: Alex Wong/Getty Images
The announcement came after Russian President Vladimir Putin said Moscow had successfully tested Poseidon, an underwater nuclear-powered drone.
Poseidon, known as Kanyon in NATO, was reportedly designed to target coastal areas and create a radioactive tsunami.
According to Putin, the weapon can’t be intercepted, and it is unmatched in speed and depth.
In his post, Trump declared the U.S. must catch up to Moscow and China when it comes to nuclear might and will no longer voluntarily observe a testing moratorium as a commitment to non-proliferation.
“The United States has more Nuclear Weapons than any other country,” Trump wrote. “This was accomplished, including a complete update and renovation of existing weapons, during my First Term in office.
“Because of the tremendous destructive power, I HATED to do it, but had no choice! Russia is second, and China is a distant third, but will be even within 5 years.”
The Arms Control Association accused Trump of “foolishly” resuming nuclear testing, while being “misinformed” and “out of touch.”
“By foolishly announcing his intention to resume nuclear testing, Trump will trigger strong public opposition in Nevada, from all U.S. allies, and it could trigger a chain reaction of nuclear testing by U.S. adversaries, and blow apart the nuclear Nonproliferation Treaty,” director Daryl Kimball wrote on X.
The short-lived war between Israel and Iran
In June, Iran fired about 100 drones at Israel, most of which were shot down, in response to an operation targeting senior Iranian military leaders and nuclear facilities.
The barrage reportedly struck at cities including Tel Aviv and Haifa, causing civilian casualties and infrastructure damage.
Damaged buildings after an missile strike in Bat Yam, Israel. Image credits: Amir Levy/Getty Images
It followed Israeli strikes—described by Prime Minister Benjamin Netanyahu as Operation Rising Lion—that killed the commander of Iran’s Islamic Revolutionary Guard Corps (IRGC), Hossein Salami.
While the two countries traded blows, U.S. forces launched coordinated strikes on June 22 against three key nuclear sites in Iran—Fordo, Natanz, and Isfahan.
Trump declared that Iran’s nuclear infrastructure had been “completely and totally obliterated” by those strikes, but top officials later acknowledged they could not confirm the whereabouts of Iran’s near-weapons-grade uranium.
Iran condemned the U.S. attacks and threatened “heavy consequences” for striking its nuclear sites.
Reports following those strikes raised doubts over their success, with estimates suggesting the June attacks set back Iran’s nuclear program by only a year or two.
An Israeli attack on the Shahran oil depot. Image credits: Stringer/Getty Images
In retaliation, Iran launched a missile at a U.S. military base in Qatar.
However, there is a suggestion that Qatar was given a warning prior to the attack, as hours before the launch, U.S. and British citizens were urged by their governments to shelter in place.
Ultimately, after a 12-day war, a ceasefire between Iran and Israel, mediated by the U.S. and Qatar, took effect on June 24.
Since then, that fragile ceasefire has held, although both sides have accused the other of breaking it on numerous occasions.
The European Institute for Security Studies noted that the 12-day war marked a dramatic break from decades of proxy-style hostilities by both Israel and Iran.
Iran and Israel traded missiles in the 12-day war. Image credits: Wisam Hashlamoun/Anadolu via Getty Images
In its analysis, the EUISS warned that deterrence now lies on shaky ground, with the scale and boldness of the June attacks restructuring what counts as “acceptable limits.”
“A future war would likely escalate, with Iran stepping up attacks on U.S. forces in the GCC and Iraq,” the institute said.
“It could also jeopardise global energy supplies through vulnerable routes like the Red Sea and Strait of Hormuz, targeted by Iran and its Houthi allies.”
The EUISS called for a relaunch of nuclear diplomacy and enhanced monitoring to prevent escalation. “A negotiated deal could roll back Iran’s programme—without the risks of a broader regional war,” it said.
China-Taiwan military escalation
Tensions in the Taiwan Strait rose sharply in 2025 as China intensified military pressure on the self-governed island, which China sees as its territory.
Chinese air and naval forces have repeatedly crossed the unofficial median line in the Taiwan Strait—a boundary that has helped maintain stability for decades.
Beijing has also sent fighter jets, bombers, and surveillance planes into Taiwan’s air-defence identification zone and has assembled warships and coastguard vessels around the island.
Chinese President Xi Jinping. Image credits: Lintao Zhang/Getty Images
It has been described as “grey-zone coercion,” a tactic designed to wear down defences and test response times, as well as pressure Taiwan towards unification.
Chatham House, an international affairs think tank, noted that the posturing around the island puts the People’s Liberation Army (PLA) in a position to rapidly pivot to a genuine blockade, or potential invasion, and with grey-zone activity now a usual occurrence, it could be difficult to identify.
Beijing has long hoped to reunify Taiwan with China through peaceful means, but it has never ruled out using military force if it deems that approach necessary.
China has stepped up pressure since the election of President Lai Ching-te in 2024, whom Beijing labels a separatist.
Taiwanese President Lai Ching-te. Image credits: Daniel Ceng/Anadolu via Getty Images
Lai has openly rejected Beijing’s ‘one country, two systems’ formula and insists Taiwan’s future must be decided by its people.
Taiwan has responded to the increased pressure by strengthening its defenses, boosting military spending, preparing a new “all-domain” air-defence system dubbed “T-Dome,” and improving overall preparedness, including civilian defence plans.
The U.S., which is bound by law to provide Taiwan with defensive support, responded by stepping up high-profile naval patrols through the Taiwan Strait and the South China Sea.
Several U.S. allies, including Japan and Australia, issued coordinated warnings and joint statements opposing any attempt to change the status quo by force, and stepped up joint maritime activity.
A Taiwanese Coast Guard boat patrols in the waters. Image credits: Daniel Ceng/Anadolu via Getty Images
Washington also approved additional arms packages for Taipei, selling it an advanced missile system worth almost $700 million amid growing concern that China is accelerating timelines for potential military action.
Raymond Greene, the de facto U.S. ambassador in Taipei, said in November, “It should be clear today and will remain clear into the future that America’s commitments to Taiwan are rock-solid.”
As noted by the Council on Foreign Relations, many foreign policy analysts fear a Chinese attack on Taiwan could draw the U.S. into a massively destructive and costly war with China.