Tension between Russia and the US has reached boiling point following Vladimir Putin's invasion of Ukraine.
NATO's military commanders have been granted the authority to deploy forces "wherever it is needed" following Russia's latest actions, with the US Secretary of Defense assuring Baltic nations they will not be on their own if faced with security threats from Russia.
But how do the US and Russia's military compare? We looked at the the International Institute for Strategic Studies' (IISS) yearly report, The Military Balance 2022, to find out.
Watch: NATO activates defence plans after Russian 'act of war' in Ukraine.
Defence Budget (2020) [US dollars] – Russia: $62.2bn, US: $715bn
Active Personnel – Russia: 900,000, US: 1,395,350
Reserve Personnel – Russia: 2,000,000, US: 843,450
Intercontinental Ballistic Missile (ICBM) Launchers – Russia: 339, US: 400.
Combat capable aircraft: Russia: 1,172, US: 1,574
Bomber aircraft – Russia: 76, US: 66
Attack helicopters – Russia: 399+, US: 740
Uninhabited Aerial Vehicles – Russia: Some (under 50), US: 416
Infantry Fighting Vehicles – Russia: 5,180, US: 2,931
Main Battle Tanks – Russia: 2,927, US: 2,645 Artillery – Russia: 4,894+, US: 5,123
Watch: Putin will see 'a stronger NATO on his flank', US Secretary of Defense says.
Ballistic-Missile Nuclear-Powered Submarines: Russia: 11, US: 14
Attack/Guided Missile Submarines – Russia: 38, US: 51
Aircraft Carriers – Russia: 1, US: 11
Cruisers, Destroyers and Frigates – Russia: 31, US: 113
Amphibious Ships – Russia: 49, US: 31
The United States Special Operations Command (USSOCOM) oversees global special operations and activities, bringing together a network of elite commands from the US Army, navy, marine corps and air force.
According to the IISS report, USSOCOM has 65,800 personnel.
Reconnaissance, hostage rescue and recovery, countering weapons of mass destruction and counterterrorism are all part of the USSOCOM mission.
Russia's Special Operations Forces are 1,000-strong, while the country has special forces units in its air, naval infantry (marines) and airborne forces.
Spetsnaz, Russian special military operators, are present in each of the five Russian military districts – the defence structure dividing military jurisdiction across the country's huge land mass.
Cyber and Space
The US Cyber Command is commanded by the National Security Agency and contains 133 Cyber Mission Teams.
Watch: RAF Chief – Russia and China 'seeking to exploit' vulnerability over space.
This is similar to the front-foot approach taken by the National Cyber Force in the UK.
Russia considers cyber a space to be protected by its armed forces, although its command chain in the domain is often blurred with civilian bodies.
Established in 2019, the US Space Force is currently being stood up and consists of 6,400 personnel.
According to the IISS report, "the development of capabilities and countermeasures is proceeding apace" for the United States Space Force.
This is a result of "peer rivals having demonstrated anti-satellite and space-control capabilities".
"This leads to a second priority – changing the US space architecture so it is simultaneously more defensible while being accessible to allies and commercial partners," the report said.
They organise, train and equip forces to protect US and allied space interest – as well as provide space capabilities to joint Combatant Commands.
The US and Russia both possess Intelligence, Surveillance, Reconnaissance equipment, while Russian Space Command leases radar technology from neighbouring states.
Both have communications and satellite equipment, although the US also possesses counter communications systems in space.
For both countries, the weaponisation of space continues – with the US and Russia developing a variety of counter-space systems.