Ahmad Massoud leads the National Resistance Front of Afghanistan fighters in the region.
He inherited his fighting spirit from his father, who fought the Soviet Union among the mujahideen until he was assassinated in 2001 at the behest of the Taliban and al-Qaeda.
Now, Mr Massoud has said: "The people of Panjshir Valley are very much united and they want to defend and... fight.
"They want to resist against any totalitarian regime, against any belief that wants to enforce their own belief and ideology upon the people."
He and several top officials from the ousted Western-backed government have gathered in the valley, establishing the last refuge and are determined to hold their ground against the Taliban.
They include Vice President Amrullah Saleh, who claims to be the caretaker leader after President Ashraf Ghani fled the country.
Watch: Who are the Taliban?
'Essentially fight a civil war': What is the resistance hoping to do?
Lynne O'Donnell, a journalist at Foreign Policy magazine who has reported on Afghanistan for a number of years, told Forces News Mr Saleh is aligned with Mr Massoud and they plan to "essentially fight a civil war".
It is from Panjshir, the last major outpost of anti-Taliban resistance, that they plan to orchestrate that "civil war".
While Mr Massoud said "in terms of personnel" the National Resistance Front "have no issue whatsoever", he acknowledged that "when it comes to equipment and resources" they are "lacking".
And Ms O'Donnell said the Taliban are now an "incredibly well-armed force".
"The Panjshiris don't have the weapons to match what the Taliban have now," she said.
"The Taliban basically sucked up everything that the Americans left behind."
However, the Taliban's complete control over Afghanistan has not yet been consolidated and pockets of resistance are reportedly appearing around the country.
"I think once we have darkness, which we will have after 31 August, there will be a lot more fighting outside of Kabul for supremacy," Ms O'Connell said.
She added the Taliban will "break down into gangs" as different factions of the group "fight for power and control".
"But you will also have, and we're a seeing it in some places, a fightback by non-Taliban, if you like, against Taliban controlling districts and provinces.
"I think that that's going to go on for some time."
Who is Ahmad Shah Massoud?
Ahmad Massoud's father, Ahmad Shah Massoud, a former mujahideen commander blocked Soviet forces in the 1980s and the Taliban in the 1990s from conquering the narrow and almost impenetrable valley.
It has, in effect, one main road in and out.
His 32-year-old son, who was trained at UK military academy Sandhurst and was taught war studies at King's College, London, hopes to emulate his father.
Ahmad Shah Massoud attained near-mythical status in Afghanistan before he was killed in a suicide bombing.
Watch: British veteran who fled Afghanistan speaks about the "guilt" of leaving his staff behind.
Defence against the Taliban
Last Sunday, Mr Massoud told Reuters that he did not want war: "We want to make the Taliban realise that the only way forward is through negotiation."
He said his fighters are ready to fight: "They want to resist any totalitarian regime."
They have vowed to resist the Taliban and are calling for Western aid to help roll them back.
Mr Massoud wrote in an op-ed for the Washington Post saying: "I write from the Panjshir Valley today, ready to follow in my father's footsteps, with mujahideen fighters who are prepared to once again take on the Taliban.
"We have stores of ammunition and arms that we have patiently collected since my father's time because we knew this day might come."
However, experts say a successful resistance is extremely unlikely and could even potentially aggravate Afghanistan's already considerable problems.