NATO–Russia relations

On 24 February 2022, Russia invaded Ukraine, starting the largest and deadliest war in Europe since World War II, in a major escalation of the conflict between the two countries which began in 2014. The fighting has caused hundreds of thousands of military casualties and tens of thousands of Ukrainian civilian casualties. As of 2025, Russian troops occupy about 20% of Ukraine. From a population of 41 million, about 8 million Ukrainians had been internally displaced and more than 8.2 million had fled the country by April 2023, creating Europe's largest refugee crisis since World War II.

On 24 November 2015, a Turkish Air Force F-16 fighter jet shot down a Russian Sukhoi Su-24M attack aircraft near the Syria–Turkey border. According to Turkey, the aircraft was fired upon while in Turkish airspace because it violated the border up to a depth of 2.19 kilometres (1.36 miles) for about 17 seconds after being warned to change its heading ten times over a period of five minutes before entering the airspace. The Russia Defence Ministry denied that the aircraft ever left Syrian airspace, claiming that their satellite data showed that the Sukhoi was about 1,000 metres (1,100 yd) inside Syrian airspace when it was shot down.

A Second Cold War, Cold War II, or the New Cold War has been used to describe heightened geopolitical tensions in the 21st century between usually, on one side, the United States and, on the other, either China or Russia—the successor state of the Soviet Union, which led the Eastern Bloc during the original Cold War.

Not One Inch: America, Russia, and the Making of Post-Cold War Stalemate is a 2021 book by M. E. Sarotte about the tensions between NATO, including the United States, and Russia in the post–Cold War era, especially those related to NATO's eastward expansion, seen from the perspectives of Russia, the USA and other NATO countries. A main part of the book is examination of whether there was a "broken promise" not to expand NATO eastwards after the reunification of Germany.

Zapad 2017 (Russian: «Запад-2017», Belarusian: Захад-2017, lit. West 2017) was a joint strategic military exercise of the armed forces of the Russian Federation and Belarus (the Union State) that formally began on 14 September 2017 and ended on 20 September 2017, in Belarus as well as in Russia's Kaliningrad Oblast and Russia's other north-western areas in the Western Military District. According to the information made public by the Defence Ministry of Belarus prior to the exercise, fewer than 13,000 personnel of the Union State were to take part in the military maneuvers, a number that was not supposed to trigger mandatory formal notification and invitation of observers under the OSCE's Vienna Document.

The Aleppo offensive (November–December 2016), code named Operation Dawn of Victory by government forces, was a successful military offensive launched by the Syrian Armed Forces and allied groups against rebel-held districts in Aleppo. The offensive came after the end of the moratorium on air strikes by Russia, and the Russian Armed Forces again conducted heavy air and cruise missile strikes against rebel positions throughout northwestern Syria. The offensive resulted in government forces taking control of all rebel-controlled parts of eastern and southern Aleppo, and the evacuation of the remaining rebel forces.

The incident at the Pristina airport was a military confrontation between the forces of Russia and NATO on 12 June 1999, following the end of the Kosovo War. Russian troops unexpectedly occupied the airport ahead of a planned NATO deployment, creating a tense stand-off. The conflict was resolved through a peaceful agreement, but also due to the potential threat posed by the Kosovo Liberation Army (KLA), which opposed the Russian presence and could have escalated the situation further.

The 1st Separate Airborne Brigade (Russian: 1-я отдельная воздушно-десантная бригада, 1ОВДБр), also referred to in English as the 1st Russian Separate Airborne Brigade (1 RSAB), was a Russian Airborne Forces unit that existed from 1996 to 2003 and was Russia's contribution to the NATO-led peacekeeping mission in Bosnia and Herzegovina, the Implementation Force (IFOR), later renamed the Stabilization Force (SFOR).

On 15 November 2022, a missile struck Polish territory, in the village of Przewodów near the border with Ukraine, killing two people. The incident occurred during attacks on Ukrainian civilian infrastructure by Russia. It was the first incident of a foreign missile (as opposed to prior UAV incursion) hitting NATO territory during the Russian invasion of Ukraine. Initially Ukraine accused Russia of striking Poland, while United States claimed that the missile was likely to have been an air defence missile fired by Ukrainian forces at an incoming Russian missile. This was later confirmed in September 2023 by the Polish Prosecutor's Office, which stated that the explosion was caused by an out of control air-defence S-300 missile.

In March and April 2021, prior to the 2022 Russian invasion of Ukraine, the Russian Armed Forces began massing thousands of personnel and military equipment near Russia's border with Ukraine and in Crimea, representing the largest mobilisation since the illegal annexation of Crimea in 2014. This precipitated an international crisis due to concerns over a potential invasion. Satellite imagery showed movements of armour, missiles, and heavy weaponry towards the border. The troops were partially withdrawn by June 2021, though the infrastructure was left in place. A second build-up began in October 2021, this time with more soldiers and with deployments on new fronts; by December over 100,000 Russian troops were massed around Ukraine on three sides, including Belarus from the north and Crimea from the south. Despite the Russian military build-ups, Russian officials from November 2021 to 20 February 2022 repeatedly denied that Russia had plans to invade Ukraine.