David Miliband is president and CEO of International Rescue Committee and a former British foreign secretary. The opinions in this article are those of the author.

(CNN) The civil war in Afghanistan is raging again. After almost 40 years of near-consecutive conflict -- from the Soviet invasion to the US-led war against the Taliban for its sheltering of Osama bin Laden and al Qaeda post-9/11 -- Afghanistan is once again on the international emergency watch list.

As we mark 15 years since that tragic morning in Manhattan, it's right to ask what international efforts have achieved in Afghanistan and what challenges lie ahead.

Violence is escalating across the country at an alarming rate. The Taliban, at their strongest since the start of the US invasion in 2001, are leading a renewed insurgency in Helmand, Kunduz and beyond.

ISIS, a new foe, is securing its presence and honing the gruesome tactics employed in Syria and Iraq -- including the suicide bomb that killed 80 in the capital, Kabul, only a few weeks ago.

In 2015, there were 11,000 civilian casualties in Afghanistan -- a record only set to be eclipsed this year, as the United Nations Assistance Mission confirms new extremes of violence. One in four of these casualties have been children.

Violations of international humanitarian law continue by various parties to the conflict, making Afghanistan not only the world's most dangerous setting for humanitarian and medical workers, but perpetuating the suffering of a population that has suffered enough. Already one of the world's poorest nations, worsening security and dwindling international investment have brought the Afghan economy to its knees.

Rising tides of violence have forced a rethink of foreign military presence in Afghanistan. NATO has committed to maintaining support to Afghan security forces through 2020 , helping sustain a struggling Afghan security force.

This must signal and demand a parallel, unyielding humanitarian commitment to Afghanistan.

The announcement of military support without amplified humanitarian support puts the fragile and hard-won gains of the past 15 years at peril -- and risks repeating its mistakes.

While news of increased violence and ever-greater humanitarian need is met with predictable fatigue from the American public, it should not obscure the hard-fought gains since 2001 that need to be preserved in Afghanistan.

Millions of Afghan men and women cast their ballots in the first democratic handover in their country's history in 2014 , resulting in the inauguration of President Ashraf Ghani.

JUST WATCHED Afghan Taliban announces new leader Replay More Videos ... MUST WATCH Afghan Taliban announces new leader 01:02

Since the fall of the Taliban, nearly 6 million Afghan refugees -- the vast majority in exile for decades -- voluntarily returned to Afghanistan.

But what could have been a watershed return has now slowed to little more than a trickle, thinning out as families lack the safety and support to return , and rebuild, at home.

Faced with insurmountable threats to their lives and livelihoods, it is no surprise that a thousand Afghans a day, on average, have fled their homes since the beginning of the year.

A staggering 1.2 million people are currently internally displaced , the highest number since the fall of the Taliban.

Afghanistan's 2.7 million refugees mostly reside in neighboring Iran and Pakistan , with hundreds of thousands -- possibly millions -- more residing there unregistered.

Hosts to Afghan refugees for decades, these two nations -- which have consistently ranked as top refugee-hosting countries as a result -- are exerting increasing pressure to return Afghans to their homeland.

JUST WATCHED ISIS claims responsibility for deadly Kabul blasts Replay More Videos ... MUST WATCH ISIS claims responsibility for deadly Kabul blasts 03:26

Unsurprisingly, Afghan families are undertaking the desperate trek towards Europe, making up a quarter of all arrivals in Greece -- but are amongst the first to be restricted entry into Europe as a flailing asylum and resettlement system teeters under pressure.

Today, the Afghan refugee population is the second-largest in the world , a dire accolade only recently surpassed by the mass flight from the horrors in Syria, and the single largest protracted refugee situation of our time.

It is not enough to say that everything depends on a political settlement, and that can only be hammered out locally and regionally. Both points are true, but do not absolve the international community of the responsibility to sustain hope and dignity to some of the most beleaguered people in the world. Three points are vital.

Afghanistan needs more money

We must, firstly and as a point of urgency, increase the sheer amount of humanitarian aid directed at Afghanistan to meet immediate and overwhelming need. This year's UN appeal, a modest figure of $339 million, is barely 40% funded.

While the problem of underfunding extends beyond Afghanistan -- UN appeals are halfway funded on average, putting lifesaving assistance the world round at risk -- at the current level of financing, we are delivering $16 in humanitarian assistance to each Afghan in need for the entire year.

Even if fully funded, the appeal would deliver just over $40 in assistance per person. This level of investment is inadequate not only to meet the immediate needs of 8 million people, but to prevent the subsequent deterioration in humanitarian conditions. A concerted boost in humanitarian assistance inside Afghanistan is of pressing importance.

More aid; better aid

Second, more aid needs to be allied to an agenda for better aid. Afghans need the different parts of the international system to target what UN Secretary-General Ban Ki-moon has called "collective outcomes" for health, education, protection and income, crossing the divide between humanitarian and development programs. Programs need to be based on evidence of what works. This is a clarion call for working more strategically with limited resources.

One example is the use of cash. Just a few days ago, the IRC launched a cash transfer program for internally-displaced and vulnerable host communities in some of Afghanistan's most inaccessible provinces, recognizing that cash is uniquely positioned to deliver flexible, cost-efficient and dignified relief. This helps families avoid the impossible choices they are forced to make in emergencies -- pulling their children out of school, buying less nutritious food, selling the little they own -- helping ease the unforgiving cycle of crisis and poverty. It also recognizes that those caught in crisis know what they need, and don't need aid agencies to tell them.

Another, and a fundamental effective intervention, is locally-led programming. The World Bank-funded National Solidarity Program is such an example.

For over a decade, the NSP has empowered Afghans to identify, and meet, their needs by awarding small grants to a national network of over 30,000 locally-elected Community Development Councils. These Councils have been responsible for thousands of local development projects, implemented with the help of NGOs like the IRC.

From rehabilitating roads to building new schools, these projects have changed the lives of 24 million people, ushering in a new era of trust between the government and its constituents across the country. Widely lauded as one of the most successful community-driven reconstruction programs in the world, the NSP is the perfect example of the kind of strategic, cost-efficient partnership that is paving the way for sustainable and lasting reconstruction in Afghanistan -- and is empowering Afghans to drive their own goals for the future.

Breaking the cycle of displacement will necessarily involve Europe, too. EU member states must come to terms with what is realistically, and morally, needed to deal with the continuing exodus towards its shores.

Proper resettlement across Europe

The third key step is for Europe to ensure a fair, thorough and effective asylum process for refugees -- Syrians and Afghans alike -- avoiding discrimination based on nationality and in support of international legal norms. In addition, EU member states must commit to a meaningful and longterm resettlement scheme that includes refugees from protracted situations.

The IRC is calling on the EU to commit to resettling 540,000 refugees over the next five years , a demonstration that Europe can take on a leadership role in this global displacement crisis and share responsibility for refugees in need. The United States must also increase its commitments to resettlement, doubling its current commitment and resettling 140,000 refugees in 2017. Resettlement is a life-saving activity, and more of it is urgently needed.

September marks an important moment for global leadership. Both President Obama and the United Nations General Assembly have convened landmark summits to galvanize concerted action in response to the unparalleled displacement crisis we face worldwide.

A new American president and a new United Nations secretary-general will need to forge ahead, carrying the torch of indispensable and invigorated solidarity with the Afghan people. Bold, practical, long-term solutions are needed for Afghanistan -- and beyond. Only then can we ensure the past 15 years, a grim anniversary we mark in September, are a foundation on which to build.