What counts as an ‘invasion,’ or as ‘lethal aid’? Here’s what some terms from the Russia-Ukraine crisis really mean.

“I wouldn’t say that’s a fully-fledged invasion, but Russian troops are on Ukrainian soil,” said Josep Borrell, the European Union’s foreign policy chief, told reporters.

“There’s no such thing as a minor, middle or major invasion. Invasion is an invasion,” Ukrainian Foreign Minister Dmytro Kuleba said at a news conference in Washington on Tuesday.

The White House initially wrestled with whether Putin’s actions constituted an invasion. But in a speech on Tuesday, Biden was explicit: Russia’s moves on eastern breakaway regions marked “the beginning of a Russian invasion of Ukraine.”

Canadian Prime Minister Justin Trudeau called it a “further invasion,” in reference to Russia’s previous annexation of Crimea in 2014 and support for separatists in eastern Ukraine.

Why are Donetsk and Luhansk in Ukraine’s Donbas region a flash point for Putin?

“What we see now is that a country that is already invaded is suffering further invasion,” NATO Secretary General Jens Stoltenberg said Tuesday.

It’s a dispute over terminology with significant implications. Western leaders have repeatedly threatened Putin with serious economic sanctions if Russia invades Ukraine. After Putin’s moves early this week, the United States and European countries unveiled a first wave of sanctions targeting Russian banks and elites.

For now, though, Western countries appear to be reserving the strongest punitive measures until Russian troops move further into Ukraine.

Here are other key terms to know related to the Russia-Ukraine crisis.

Line of control; Breakaway republics

The “line of control” refers to the roughly 260-mile divide in eastern Ukraine separating areas held by Russia-backed separatists from territory controlled by Kyiv-government forces. When Russia invaded Ukraine in 2014 and annexed the Crimean Peninsula, separatists proclaimed “people’s republics” — often referred to as “breakaway republics” — in the east. Fighting in the area has claimed 14,000 lives since 2014.

In Ukraine's separatist Donbas region, war is an ever-present reality

The separatists claim all of Donetsk and Luhansk in the Donbas region as their territory, but they control about one-third of the region along the border with Russia. Moscow has recognized the separatists’ territorial claims beyond the current line of control, raising fears that Putin intends a large-scale invasion.

Shelling

Shelling is a feature of life in eastern Ukraine. It refers to the shooting of a projectile — or shell — which contains an explosive, incendiary or chemical filling, usually fired by artillery. The Ukrainian military has also reported separatists firing mortar and grenade launchers along the front.

The Ukrainian Armed Forces said Saturday that shelling in the government-controlled side of the region had increased “tenfold” since last Thursday. Artillery shells hit a kindergarten there last week. On the other side of the line of control, in the separatist enclave in Donetsk, the scars of previous bouts of shelling linger.

In Ukraine’s war-weary east, intensifying shelling and battered homes signal attempts at provocation by Russia

Defensive weapons

The term “Defensive weapons” sounds contradictory. Officials often use it to describe a category of weapons — including antitank missiles and antiaircraft missile systems — meant to defend against an attack. They have limited range and destructive capacity.

Biden said Tuesday that the United States would continue to supply “defensive” weapons to Ukraine. The U.S. rushed anti-armor missiles and other weapons to Ukraine in January and February. Britain, Poland and other European countries have also used the term to describe their own weapons shipments to Ukraine. Diplomats are careful to use the term in the face of accusations that supplying weapons to Ukraine could threaten Russia.

But some have questioned the notion that any weapon could be defensive. At least one Western country remains skeptical of the idea: Germany has declined a request from Ukraine for “defensive weapons” such as anti-drone rifles and portable surface-to-air missiles, citing long-standing policy against sending arms to conflict zones.

Lethal aid

“Lethal aid” is military aid designed to kill people, while “nonlethal aid” can refer to basically anything else, including communications equipment and medical supplies. Make no mistake: When officials say “lethal aid,” they mean deadly weapons.

The distinction can be vague, but it’s legally significant — the State Department can authorize the distribution of nonlethal aid, while lethal aid requires a presidential directive and a briefing to congressional leaders.

A tweet from the U.S. Embassy in Kyiv on Jan. 21 announced the arrival of “close to 200,000 pounds of lethal aid” to Ukraine as part of an additional $200 million in military aid approved by Biden in late December. The embassy specified that this included ammunition for Ukrainian troops on the front line.

Some commentators have criticized the term, arguing that it obscures the meaning and significance of the weapons and ammunition in question.

What are economic sanctions, and how did they become Washington’s foreign policy tool of choice?

Targeted sanctions

“Targeted sanctions” are meant to minimize the suffering of civilians. They can include travel bans, asset freezes, arms embargoes and trade restrictions.

The Biden administration on Tuesday imposed its first tranche of sanctions targeting Russia for its actions against Ukraine. It included the freezing of assets of two state-owned banks.

European leaders have also pursued targeted sanctions against Russia. Asked whether the White House would impose sanctions against Putin himself, a senior Biden administration official told The Post that “all options remain on the table.”

What is NATO, and what is its role in the Russia-Ukraine crisis?

NATO

The North Atlantic Treaty Organization, and Ukraine’s ability to join it, lies at the center of the conflict between Russia and Ukraine. NATO was formed in 1949 and designed as a bulwark against the former Soviet Union. The military alliance, which initially had just 12 members, has since grown to 30 countries.

The government of Ukraine, which is not a NATO member, hopes the country can one day join the alliance. NATO countries have signaled that is unlikely to happen soon but have insisted on keeping the “open-door” policy. Russia sees NATO’s expansion as a threat and has demanded that Ukraine be prevented from ever joining the alliance.