Understanding the weapons that have drawn the world’s attention since Russia’s invasion of Ukraine

Russian officials claimed Wednesday to have fired long-range naval cruise missiles into Ukraine. If confirmed, that would add to the roster of weapons Russia has used in its invasion — some new or cutting-edge — that have drawn the attention and concern of analysts.

Some Western experts worry that Moscow, amid pressure to escalate in the face of mounting losses, could go even further, using chemical weapons or even tactical nuclear weapons.

But Ukraine has weapons, too, many of which its Western allies have supplied. Antitank weapons, including the Javelin missile sent by the United States, have become a symbol of Ukrainian resistance. Not only have drones made by Turkey hit Russian targets but footage of the strikes has become a win on the social media battlefield.

Here are some of the weapons that are in use, or that experts fear could have a role in the conflict.

What missiles is Russia using?

On Monday, President Biden confirmed Kremlin claims that its forces had used hypersonic missiles against Ukraine. These weapons, which can travel faster than five times the speed of sound, have not been used in conflict before.

In theory, a fast-moving, maneuverable missile like this could be used to devastating effect, potentially even at long range. However, U.S. officials have downplayed the threat posed by Russia’s hypersonic technology. The United States and China also have advanced hypersonic programs, though neither has gone beyond tests.

Russia’s weapon is named Kinzhal — Russian for “dagger.” A modified version of Russia’s ground-launched Iskander missile, it is an air-launched ballistic missile that can be maneuvered to hit a target or dodge defenses. Russian officials say the missile was used last week to hit an ammunition depot in western Ukraine.

On Wednesday, Russia said it had also used a long-range cruise missile called Kalibr in an attack on Ukrainian forces earlier in the week. The missile, which can be launched from sea, was first used by Russian forces in Syria. U.S. officials said they could not confirm that the weapon had been used.

What about cluster and thermobaric ‘vacuum’ weapons?

Russia has also been accused of using or preparing to use cluster munitions and thermobaric weapons, often called “vacuum” weapons.

Cluster munitions are rockets, bombs or other projectiles that scatter small bomblets. Because they end up indiscriminately hitting a wide area, they can pose a large risk to civilian populations, even if they are not specifically targeted.

Rights groups have documented the use of cluster munitions by Russian and Syrian government forces in the Syrian civil war. Early accounts from Human Rights Watch and others suggest that they have been used in Ukraine, too.

An international treaty bans the use of cluster munitions, but Russia is not a signatory to it — and neither are some other large counties, including China and the United States. Ukraine was accused of using cluster munitions against Russian-backed separatists in 2014 and 2015; it has denied it used them.

Thermobaric weapons are designed to cause intense heat and pressure. Typically launched from tanks, the missiles explode in two stages, first distributing an aerosol before a second charge ignites the cloud. The ensuing explosion produces an extreme blast and burns up oxygen in the area.

They are often called “vacuum” weapons because of the way they suck up oxygen, though the idea that they can suck air out of people’s lungs is mistaken. They are infamous for being nearly impossible to escape because the flammable gas can seep into enclosed structures.

“Let’s say you have people hiding, maybe civilians, in a basement,” Dan Wasserbly, head of Americas news at Janes, an open-source defense intelligence agency, told The Washington Post. “That doesn’t protect them against something like this, because the aerosols get into the basement and catch fire and everybody dies a pretty awful death.”

Russia’s thermobaric launch system is called the TOS-1A, though troops call it a “flamethrower,” for obvious reasons. British officials say Russia has admitted deploying them to Ukraine, despite official Kremlin denials.

Has Russia used chemical weapons, including white phosphorus?

Russia has alleged that the United States has biological weapons labs in Ukraine, which the White House has denied. But when it comes to toxins, the Kremlin itself has a lengthy history of developing and using chemical weapons.

Some experts point to the use of a nerve agent called Novichok to target a former Russian spy living in England as evidence of Moscow’s willingness to use such tactics.

“Russia used chemical weapons, in peacetime, in a foreign country. The thought that they might now use chemical weapons in Ukraine is entirely rational,” Andrew C. Weber, a top nonproliferation official for the Pentagon in the Obama administration, told The Post.

Russia was also allied with the Syrian government of Bashar al-Assad, whose troops repeatedly used chlorine gas to force rebels out of their hiding spots in urban areas, despite the risk to civilians.

Both Russia and Syria joined the United States and 190 other countries in signing the Chemical Weapons Convention, which was drafted in 1992 and became effective in 1997. But U.S. officials say Russia hasn’t been in compliance with the convention for years and could pursue an attack using chemical weapons in Ukraine.

Ukraine has accused Russia of using white phosphorus. A controversial substance that some military analysts consider a chemical weapon, it is often used by militaries to create smokescreens, as it creates a thick white cloud. U.S.-led coalition forces used the munitions against the Islamic State in Iraq and Syria in 2017, according to rights groups.

The substance can cause severe chemical burns, and its smoke can poison humans and animals.

Could Russia use nuclear weapons?

Given the high stakes for Russian President Vladimir Putin in Ukraine, some experts have said they are worried about the possibility, however slim, that the war could escalate to the point that Russia turns to nuclear weapons.

Of particular concern are the smaller nuclear weapons developed by Russia in recent years. These weapons are dubbed “tactical” nuclear weapons because they are designed for battlefield use, rather than devastating attacks like those made on Hiroshima and Nagasaki by the United States in World War II.

Tactical nuclear weapons are not regulated by any arms control treaty. They have never been used in a conflict, but Russia is thought to have about 2,000 of them. They are small enough to be fitted onto a missile — perhaps even a hypersonic one like those already used by Russia in Ukraine.

Such a weapon would allow Russia to show off its nuclear might but, if deployed in a relatively cautious way, let it avoid the prospect of mutually assured destruction.

But even a tactical nuclear weapon would carry large risks of sparking a broader nuclear conflict. U.S. senators have said that if nuclear fallout were to drift over a NATO ally, it could well be considered an attack.

What about the missiles and drones going to Ukraine?

Though much of the focus is on Russia’s weapons, Ukrainian forces have also made use of technology that, if not new, is new to them — most notably antitank missiles and drones.

Shoulder-mounted Javelin missile systems supplied by the United States have been used to great effect to target Russian vehicles that emit heat, including tanks. The high-tech weapons are known as “fire-and-forget” missiles because they lock onto a target and do not require further guidance from the gunner.

Other countries have supplied similar weapons, including British-made NLAWs, or Next Generation Light Anti-Tank Weapons, which are less sophisticated but lighter and cheaper than U.S.-made Javelins. The United States has also supplied Stinger missiles, a human-portable weapon designed to take out low-flying aircraft.

For Russian vehicles, the threat comes not just from these weapons but from above. The Bayraktar TB2, a Turkish-made unmanned aerial vehicle, has proved particularly useful. These drones use lasers to guide bombs toward Russian forces, who are left unaware in part because Moscow has not been able to set up air defense systems in Ukraine. Footage of the destruction, also filmed by the drones, has proven a key tool in Ukraine’s information war.

The United States has also supplied Switchblade drones to Ukrainian forces. There are two variations of these small unmanned aircraft — one, the 300 model, weighs up to five pounds and flies for as long as 15 minutes at a time. The 600 model weighs about 50 pounds and flies for as long as 40 minutes and can target armored vehicles.

These drones are known as “kamikaze” drones because they fly into their targets.