In just a few days, Ukraine and Russia appear to have significantly upped their weapons capabilities.

First, Washington gave Kyiv long-awaited approval to use Western-made longer-range missiles on targets inside Russian territory.

Then US President Joe Biden agreed to give Ukraine anti-personnel land mines, a step that could help slow Russian advances in its east.

This decision has drawn condemnation from human rights groups over the risks posed to civilians. 

The flurry of last-minute policy changes comes two months before Donald Trump, who has vowed to swiftly end the war, is set to take over the White House.

Late on Thursday, Kyiv claimed Russia used an intercontinental ballistic missile (ICBM) for the first time.

Russian President Vladimir Putin denied this, saying his country had fired a new mid-range ballistic missile.

Experts say Russia and Ukraine will be using the coming months to secure the strongest position they can before any Trump-negotiated talks. 

What is the significance of using ICBMs?

On Thursday, the Ukrainian government accused Russian forces of firing an ICBM into its territory.

"All the characteristics – speed, altitude – are [of an] intercontinental ballistic [missile]. An expert [investigation] is currently underway," Ukrainian President Volodymyr Zelenskyy said in a video statement.

But Mr Putin later rejected this, instead saying Russia's military had fired a new hypersonic, mid-range ballistic missile at a Ukrainian military facility.

These weapons are capable of carrying a nuclear warhead thousands of kilometres but a Ukrainian air force source told AFP it was "obvious" this weapon did not carry an atomic charge.

Oslo University missile technology and nuclear strategy researcher Fabian Hoffmann said the range of the missile was of little importance.

But he said the technology inside the so-called Oreshnik missile was far more menacing.

"The fact that it carried a MIRVed [Multiple independently targetable reentry vehicle] payload is much more significant for signalling purposes and is the reason Russia opted for it," he said.

"This payload is exclusively associated with nuclear-capable missiles."

What are anti-personnel mines?

Anti-personnel mines are exactly what the name says.

These are designed to target people, not machines.

Michael Shoebridge, director and founder of Strategic Analysis Australia, said they often look like tin cans or small discs.

"Land mines target things like armoured vehicles and they're much bigger," he told the ABC.

"But these mines that the Americans are supplying will be triggered by someone stepping on them or by proximity of a person."

The US has been providing Ukraine with anti-tank mines throughout the war.

Defence Secretary Lloyd Austin said the anti-personnel mines were now needed to help Ukraine stall Russian progress on the battlefield.

Moscow's forces are moving in smaller ground units on the front lines rather than in more heavily protected armoured vehicles.

Ukraine has "a need for things that can help slow down that effort," Mr Austin said during a trip to Laos.

The decision to provide the mines has been criticised by humanitarian organisations.

An international treaty agreed to by 164 state parties, 133 countries prohibits the use of anti-personnel mines.

The US and Russia are not signatories, but Ukraine is.

Amnesty International called the US decision "reckless" and a "deeply disappointing setback".

Human Rights Watch director Mary Wareham said the vast majority of people killed and maimed by anti-personnel mines were civilians.

"About a third of casualises are children," she told ABC News Channel.

She said the types of mine the US intended to send were "old obsolete stocks", which raised questions about whether they would function as intended.

The US said it would provide non-persistent mines, different to what Russia had been using.

They are said to be electrically fused and powered by batteries.

Once the battery runs out, the landmines will not detonate, and they can become inert within four hours to two weeks. 

How is Ukraine using ATACMS?

It didn't take long for Ukraine to unleash its first strikes on Russia using longer range Army Tactical Missile Systems (ATACMS).

Within 24 hours of the US lifting its restriction on attacking Russia, Ukraine fired six ATACMS into the Bryansk region, hitting an ammunition depot.

The Bryansk region of western Russia is about 112 kilometres from the Ukrainian border. 

ATACMS have a range of up to 300km, and can carry 225 kilogram fragmentation warheads designed to engage high-value targets such as air fields and missile sites.

"ATACMS are powerful ballistic missiles, so they fly extremely high, very fast, and then come down extraordinarily fast making them hard to intercept," Mr Shoebridge said. 

Kyiv has wanted the long-range capabilities to counter glide-bomb attacks from Russian airfields, and to strike military command and control hubs, and target fuel and weapons depots.

The Institute for the Study of War (ISW), a Washington think-tank, has estimated about 250 Russian military "objects" were in reach of ATACMS.

ATACMS can be fitted with two types of warheads.

There is a single 225kg high explosive variant, which would be used to hit one large target and cause a lot of damage.

The other is a cluster munition, which drops hundreds of bomblets and could be used against concentrations of troops.

"They disperse a bit like dandelion seeds and can strike a broader area," Mr Shoebridge said.

ATACMS are the longest-range missiles that Washington has provided Ukraine, but Kyiv also has access to long-range Storm Shadows missiles, developed by France and the UK.

According to several British media outlets, citing sources familiar with the matter, they were also used in Russia for the first time this week.

Storm Shadows are low-flying missiles, which can carry a payload up to 400kg.

Mr Shoebridge said depending on the payload, it could reach a range of 500km.

Will any of it make a difference?

The war reached its 1,000-day milestone on Tuesday.

And recently, it has largely been going Russia's way with its bigger army slowly pushing Ukraine's forces backward in the eastern Donetsk region.

Ukrainian civilians have also been facing increasing large-scale Russian drone and missile barrages.

Mr Shoebridge said given the state of the war, Ukraine needed the weapons approvals from the US more than a year ago.

"I think President Biden is acting a bit like a primary school student who had a year to do a whole bunch of homework, and is now trying to get it all done in the last couple of weeks," he said.

Jennifer Kavanagh, director of military analysis at Defense Priorities, said ATACMS were not the answer to change the course of the war.

"To really impose costs on Russia, Ukraine would need large stockpiles of ATACMS, which it doesn't have and won't receive because the United States' own supplies are limited," she told AP.

"The biggest obstacle Ukraine faces is a lack of trained and ready personnel, a challenge that neither the United States nor its European allies can solve and that all the weapons in the world won't overcome."

With the missiles being in short supply, Ukraine would need to be strategic in how they are used.

Russia's Kursk region would likely be a priority, Mr Shoebridge said.

About 10,000 North Korean troops recently arrived in Kursk to help Moscow retake territory Ukraine has held since August. 

Russia had been suffering from some of its highest rates of casualties in months, and there were signs their Soviet weapons stockpiles were "massively depleted," Mr Shoebridge said.

"Russia's ability to sustain the tempo of the war is really in doubt, but Ukraine is the smaller military, and it's got similar manpower problems," he said.

"Both sides will actually be wanting to establish their greatest position of strength right now.

"They both realise that if there's going to be some kind of negotiation to end the war, they want to do so from the strongest position they can end."