JUST days ago in London, I listened with sadness and shock as Ahmad Jarba and leaders of the moderate Syrian opposition described how ordinary Syrians with no links to the civil war are forced to eat stray dogs and cats to survive a campaign of deprivation waged by the Assad regime.

The world already knows that Bashar Assad has used chemical weapons, indiscriminate bombing, arbitrary detentions, rape and torture against his own citizens. What is far less well known, and equally intolerable, is the systematic denial of medical assistance, food supplies and other humanitarian aid to huge portions of the population. This denial of the most basic human rights must end before the war’s death toll — now surpassing 100,000 — reaches even more catastrophic levels.

Reports of severe malnutrition across vast swaths of Syria suffering under regime blockades prompted the United Nations Security Council to issue a presidential statement calling for immediate access to humanitarian assistance. To bolster the UN’s position, every nation needs to demand action on the ground — right now. That includes governments that have allowed their Syrian allies to block or undermine vital relief efforts mandated by international humanitarian law.

Simply put, the world must act quickly and decisively to get life-saving assistance to the innocent civilians who are bearing the brunt of the civil war. To do anything less risks a “lost generation” of Syrian children traumatized, orphaned and starved by this barbaric war.

The desperation can be eased significantly, even amid the fighting. Working through the regime, with assistance from Russia and others, inspectors from the Organisation for the Prohibition of Chemical Weapons are proving every day that professionals can still carry out essential work where there is political will. If weapons inspectors can carry out their crucial mission to ensure Syria’s chemical weapons can never be used again, then we can also find a way for aid workers on a no less vital mission to deliver food and medical treatment to men, women and children suffering through no fault of their own.

The US government has undertaken significant efforts to alleviate the suffering. Since the beginning of the Syrian crisis, the United States has led international donors in contributing nearly $1.4 billion for humanitarian assistance. Aid has been distributed to every section of Syria by leading international agencies, including the UN Refugee Agency, the World Food Program, the International Committee of the Red Cross, the Syrian Arab Red Crescent, and top-notch non-governmental groups.

Most of these aid workers are courageous Syrians who risk their safety to cross shifting battle lines for the good of others. They have performed miracles and saved thousands of lives. In return, they have been subjected to a catalogue of horrors. They have been harassed, kidnapped, killed and stopped at every turn from reaching the innocent civilians desperately clinging to life.The obstacles exist on both sides of the war. Outside observers from the UN and non-governmental organisations have chronicled the ways in which extremist opposition fighters have prevented aid from reaching those in need, diverting supplies and violating the human rights of the people trying to deliver them.

But it is the regime’s policies that threaten to take a humanitarian disaster into the abyss. The Assad government is refusing to register legitimate aid agencies. It is blocking assistance at its borders. It is requiring UN convoys to travel circuitous routes through scores of checkpoints to reach people in need. The regime has systematically blocked food shipments to strategically located districts, leading to a rising toll of death and misery.

The UN statement earlier this month calls on all parties to respect obligations under international humanitarian law. It sets out a series of steps that, if followed, would go a long way in protecting and helping the Syrian people. Convoys carrying aid need to be expedited. Efforts to provide medical care to the wounded and the sick must be granted safe passage. And attacks against medical facilities and personnel must stop.

Merely expecting a regime like Assad’s to live up to the spirit, let alone letter, of the Security Council statement without concerted international pressure is sadly unrealistic. A regime that gassed its own people and systematically denies them food and medicine will bow only to our pressure, not to our hopes. Assad’s allies who have influence over his calculations must demand that he and his backers adhere to international standards. With winter approaching quickly, and the rolls of the starving and sick growing daily, we can waste no time. Aid workers must have full access to do their jobs now. The world cannot sit by watching innocents die.

John F. Kerry is the US Secretary of State

By arrangement with The Washington Post/Bloomberg News Service