It took multiple checkpoints, identity checks and a long walk through the blacked-out corridors of the presidential compound to meet Ukraine's Deputy Prime Minister, Iryna Vereshchuk.
In an Australian exclusive, ABC's Four Corners interviewed Ms Vereshchuk inside President Volodymyr Zelenskyy's heavily fortified compound in Kyiv.
We had been in the besieged city for four days, with Russian army attacks intensifying in surrounding suburbs, when we got the call to meet Ms Vereshchuk.
In the deserted historic centre of Kyiv, soldiers manned defensive positions in the streets around the compound. Others were sawing off tree branches that could offer cover for snipers.
An armoured personnel carrier stood sentinel outside the President's office.
Shots cracked suddenly in the still air, soldiers ran shouting down one of the cobbled streets. Everyone in Kyiv is jumpy, with reports that Russian saboteurs are in the city.
All the windows at the compound were sandbagged, with gaps for guns to poke through.
In darkness, a soldier led the Four Corners team through long corridors, the only light inside coming from his head torch.
Voices urged us to move quickly. Our sense sharpened of the threat Zelenskyy and his ministers face by remaining here.
We turned finally into a well-lit room, the green back wall instantly recognisable as the place where the President has delivered some of his most powerful speeches.
Moments later, Ms Vereshchuk walked in, talking urgently on her phone. Hanging up, she told us she was responding to problems at the Russian-occupied Chernobyl nuclear plant around 100 kilometres north of Kyiv.
While Mr Zelenskyy has been commanding international headlines and praise, less is known about the Deputy Prime Minister.
As some MPs within the Ukrainian government are taking up arms for the first time after Russia's invasion of the country, Ms Vereshchuk had served as an officer in the Ukrainian army for five years.
The 42-year-old has also practised karate, hand-to-hand combat and Thai boxing.
She displays the same defiance that Mr Zelenskyy has come to embody.
"They will not succeed," she said. "Kyiv will not be taken by the Russians. Otherwise, we will all die here, together with the Russians."
Part of Ms Vereshchuk's wartime role is to organise the evacuation of civilians from towns under Russian bombardment.
On the day we met she was trying to get civilians out of the suburbs around Kyiv, Irpin, Hostomel and Bucha. The Russians had been targeting them as they tried to escape.
"Russians are committing war crimes everywhere," she told Four Corners.
"Every day and every hour, war crimes are committed against humanity, against civilians, according to all international conventions, law and principles."
Mr Zelenskyy and his ministers have been lobbying the West to create a no-fly zone over Ukraine.
Without it, Ms Vereshchuk said, Ukraine would struggle to defeat the invading Russians.
"It's going to be very hard for us to [defeat them]," she said. "The Ukrainian army and the Ukrainian spirit prevail and we are highly motivated. We are on our own land. We are defending our families, but Putin's number of jets, bombers and other weapons significantly outnumber ours."
A deal proposed by the Polish government to deliver MiG-29 fighter jets from the US military base in Germany was rejected by the US government.
"I don't understand why we cannot do it as quickly as is necessary. We are suffering in the sky. We are really losing in the sky," Ms Vereshchuk said.
She argues that Russia's attack on Ukraine threatens the rest of the world too.
"I understand that you may not care about the death of my child or my friend, but you should care about your family and your safety. Because it is an issue of our global security," she said.
"Leaders responsible for global security have to decide if they are prepared to have a person in the world who, because of his morbid ideas of what the world should look like, makes decisions that endanger the whole world and the existence of humanity."
Russian President Vladimir Putin, she said, wanted "absolute total elimination" of Ukraine.
"Putin is punishing us for trying to become free, democratic, European," she said, "to become what we have always had the right to be: a people with their own opinions, freedom of speech, freedom of choice.
"We choose our own government. We cannot be told where we should go and what organisation we can join. This is what we are paying such a huge price for now."
Mr Zelenskyy last week acknowledged that Ukraine would not become a NATO member, a significant concession, given one of Mr Putin's key demands before the invasion was that its membership of NATO be ruled out indefinitely.
Mr Putin's invasion has created divisions among NATO countries. Poland is working hard to strengthen the resolve of its partners.
It is telling that Bartosz Cichocki, Poland's ambassador to Ukraine, is the only European ambassador still in the country.
During Mr Cichocki's interview with Four Corners at the Polish embassy, the air raid signal sounded.
"Bombs are coming. We move to the shelter, Come! And do not film," he said.
We hurried through the deserted corridors of the embassy.
The bunker was a basement storeroom, with stacked gilt chairs and a pool table hidden beneath a large cloth.
With old world European manners, Mr Cichocki brushed dust from the chairs and made coffee for us in an espresso machine balanced on the pool table.
After 45 minutes, we went back upstairs to one of the embassy's reception rooms. It was empty of decoration. The flags and national symbol of Poland, the eagle, had been shipped back to Warsaw at the start of the war to prevent them falling into the invaders' hands.
Mr Cichocki is proud to have remained in Kyiv, despite the obvious danger.
"We will not leave the Ukrainians. And for me … It's a source of pride to stand, arm to arm, with the bravest nation in the world," he said.
He said it would take further "genocide" of Ukrainian civilians to change NATO's position on the implementation of a no-fly zone.
"I don't think there may be anything more extreme than what happened to Kharkiv, Irpin and Bucha," he said, "but there are still many cities left untouched."
Unlike some of its NATO partners, Poland is defiant in the face of Mr Putin's threats.
"I think we don't care anymore. Because this is our security," Mr Cichocki said.
"If Ukraine falls, we will be in big trouble. I believe the implementation of the Russian plan to create a grey zone in central Europe would start, and it would be implemented with the use of force, or a blackmail of force," he said.
And, he said, for Poland that would mean a "second-class NATO membership".
Whatever happens, he said, Mr Putin's invasion of Ukraine would force a new order on Europe.
"I believe that we'll now make further steps within NATO, within the United Nations to adjust," he said.
"And I believe those systems, the United Nation systems, will have to change. NATO, as well, OSCE [Organization for Security and Co-operation in Europe], and others.
"I think they would be completely different after whatever happens."
He described the invasion of Ukraine as the biggest crisis Europe had faced since World War II, threatening danger well beyond the borders of Ukraine.
"Very much dangerous. I think the inner circle of President Putin should take care that the red button is nowhere close to President Putin's fingers," he said, ominously.
While regime change in Kyiv appeared to be one of the early objectives of the Russian invasion, at the southern end of the country, Ukrainians say Russian forces are seeking to cut off the country's access to the Black Sea and, possibly, capture the famous port city of Odesa.
The city's Mayor, Gennadiy Trukhanov, told Four Corners he believed Russia had two possible objectives.
"Either to occupy the entire country and install a puppet government and president, or to divide the country into whatever parts they want."
Taking Odesa, he said — with its major maritime infrastructure — was a crucial goal of Mr Putin's.
"Putin already has a port for his navy base in Crimea, and I think it's sufficient for his needs in the Black Sea," Mr Trukhanov said.
"Odesa is of greater interest as a trading port, as a significant logistics centre and major trans-shipment hub … Greater Odesa has seven seaports."
As well as its strategic significance, Odesa holds a special place in Russian history, founded in the 18th century by Empress Catherine the Great.
However, Mr Trukhanov said, Ukraine's third-largest city — often described as "the pearl of the Black Sea" — holds a unique place in the hearts of its people.
"We call Odesa 'Mama'," he explained. "It's the only city in the world whose name we pronounce as tenderly as we do the most sacred word, Mama," he said.
"Of course, this city is of interest to them. They're interested in occupying it. They're interested in taking it."
The most prized public monuments and statues in Odesa have now been sandbagged for protection against Russian bombs.
Four Corners went with a military escort to defensive positions on the Black Sea where the Ukrainian 28th brigade was preparing for Russia's next advance.
For days the Russian army had been battering the city of Mykolaiv, a city east of Odesa.
The commander, Lieutenant Ivan, explained that the Russians needed their ground troops to break through in order to link up with an amphibious assault from their navy in the Black Sea.
Despite some success by Russian troops in the south, taking the city of Kherson for example, the lieutenant remained contemptuous of Russia's military tactics.
"Knowing their tactic of using humans as cannon fodder, they might try to land marines without any support from ground forces. So we're waiting for them to land," he said.
In contrast to its slow progress in the North around Kyiv, the Russian army has taken more territory in the south, including the port city of Kherson.
Lieutenant Ivan explained the Russians could move from there to cut off the Ukraine army from supply lines.
“This is the coast to which all supplies come … The enemy might hit Mykolayiv from the rear and totally sever our supply train. And then he might keep going through the regions and encircle us. This is high stakes.”
The Ukrainian army's success in holding up the Russian invasion so far has surprised analysts across the world.
One reason is that many of the soldiers fighting now are veterans of the eight-year war in the Donbas region of eastern Ukraine, where the army has battled Russian-backed separatists since 2014.
"Most of our military units are already experienced in combat. It's like in the Middle Ages: The novice will never beat the master swordsman. Our people are experienced fighters, and they have the guts to pull the trigger," he told Four Corners.
Like all of the Ukrainians we met, from senior ministers in the presidential compound to storekeepers in Kyiv, the soldiers of the 28th Brigade in their beachfront positions are defiant and certain of victory against the Russians.
Lieutenant Ivan pointed at the water lapping on the shore in the sunshine: "We'll turn the Black Sea red."
