Congo M23 rebels. Jerome Delay/Press Association. All rights reserved. Over the past three decades, the face of fighting has changed significantly. In 1986, Soviet Leader Mikhail Gorbachev and US President Ronald Reagan were conducting arms talks, while mass uprisings and violence were breaking out in Northern Ireland.

Today the Cold War is over. In fact, the quiet good news story of the last three decades was that, after a spike in armed violence at the end of the Cold War, the zone of peace globally was expanding. In 1990 there were 50 wars; by 2010 – there were 30 wars, with fewer people killed in violent conflict and key peace deals being hammered out in Myanmar, in Colombia, in the Philippines.

Sadly violence is now on the rise again - from the brutality of Syria to inter-community violence in places like the Democratic Republic of Congo, to violence linked to crime and gangs as in many parts of Latin America and the Caribbean. Global challenges, such as the rise in violent extremism and climate change, are ever-growing threats to peace. By 2014, people were fighting 40 wars, with terrorism reaching an all-time high, and battle deaths reaching a 25-year high.

But while the political and social contexts have changed, the international community meetings for the UN General Assembly this September must surely get better at learning the lessons of the past – about how to prevent conflict and build peace. In the 30 years since International Alert was set up in 1986, we’ve learnt plenty about what does and doesn’t work when it comes to resolving and preventing conflict. Here are four lessons we can keep in mind.

Peacebuilding must happen before, during and after violent conflict

Some people imagine that peacebuilders rush in after war like an ambulance to treat the wounded. That is indeed badly needed. But prevention is surely better than cure, and peacebuilding is at its best when no-one has ever heard about it – because action taken early has prevented bloodshed.

The focus on prevention has been underlined by the 2015 UN review of peacebuilding. As UN Deputy Secretary-General Jan Eliason put it: "We must invest more in the peacebuilding which is needed to prevent violence – not just after an explosion of conflict. Otherwise we pay a horrible price later on.”

Peacebuilding needs to happen even in the midst of war: the warring parties need to feel their people’s thirst for peace in order to sit at the table and negotiate a deal. They need to know they have a mandate – and they need to feel the pressure to settle.

Equally, work at the grassroots to heal the wounds of war cannot start a moment too soon – to mitigate further violence and lay the foundations for a future peace. For example in Syria, where so many children have known nothing but war, peace education classes can give them a chance to receive trauma healing and the space to express their anger. As one Syrian teacher told me: “We must keep going, we must believe in the next generation.” Meanwhile, businesses can also help de-escalate the conflict in the country by providing much-needed livelihoods that provide the economic underpinning for peace and re-build bridges between communities.

Peacebuilding takes time

Peacebuilding is slow. It needs patient long-term investment by governments.

Twenty years after the genocide, the people of Rwanda have made remarkable progress – but the scars of the war are yet to fully heal. It takes years for people to forgive those who have killed their families, or to recover from torture, or build back their shattered livelihoods. Trauma healing and dialogue sessions, along with opportunities to do business together, can support this process.

Even the fastest-changing countries have taken between 15 and 30 years to raise their institutional performance from that of a fragile state today – Haiti, for example – to that of a functioning institutionalised state, such as Ghana. Institutional performance is a key indicator of more peaceful societies. Addressing other contributors to conflict, such as the trust-eroding force of corruption have taken, at their fastest, 27 years.

In the 1980s, Alert started working in Burundi - where people made huge progress. But the attention-span of the global community often does not match the long term nature of change and is much lower than the determination of the powerful to stay in power. And today Burundi is spiralling back towards violence, all the early-warnings ignored. 

The international community must not walk away from countries once a peace deal is signed but continue to address the root causes of conflict that brought about violence – such as poverty, inequality, poor institutions and corruption – to ensure it does not break out again.

Peacebuilding needs investment

Peace doesn’t fall from the skies. It is won through difficult, tireless work – building societies where people feel they have a say in the decisions that affect them,  where they have job opportunities, working with women leaders, with victims and perpetrators, businesses, and with the future custodians of peace – youth. It also has to be won little tiny peace by little tiny peace; down on the ground inch by inch, helping each child talk about their trauma or each mother express her rage – just as people making an area safe from unexploded landmines, have to work literally inch by inch to clear the debris of war, to make a community safe again.

That needs investment. The cost of world military spending is US$1.7 trillion, according to the Stockholm International Peace Research Institute (SIPRI). Meanwhile, according to the latest Global Peace Index the total cost of conflict is a mind-boggling US$ 14.3 trillion. That is 11 times the size of total foreign direct investment, and eight times more than we invest in peacekeeping (US$ 8 bn). By comparison, we invest a puny $6.8 billion in long-term peacebuilding. 

Just as we invest billions in training and equipping the military so that we can ‘win’ wars, let’s invest in training and equipping people for the harder task of winning and sustaining peace. If it takes time to train people to use guns, it takes even longer to train them not to use guns.

And this can be great value for money. Poverty thrives on conflict – while countries that are more peaceful can become more prosperous, stimulating the global economy. Not to mention that peace is definitely better for human happiness.

The two 2015 landmark UN reports on peacebuilding architecture and peace operations throw up a flare that we are not investing enough. The Sustainable Development Goals, Goal 16 in particular, have recognised peace as a pre-requisite for global development, while the World Humanitarian Summit in May acknowledged that the humanitarian system is unsustainable unless something is done about prevention. We have the resolutions – now we need the reality. 

Peacebuilding has to take place at multiple levels

Peacebuilders live in skyscrapers not bungalows. You need to build peace at all levels – from the peace deals signed in the revolving glass-restaurant on the top, right down to the very deep foundations, addressing land reform or other structural inequalities that are the base of the conflicts. Otherwise, the peace deal thrashed out by the warring parties will not hold. In fact, half of all peace deals collapse back into war after five years. Because the underlying causes of the conflict have not been addressed, and peacebuilding is not taking place right across society.

Peace is as much about communities living side by side and resolving their differences, about building everyday peace, as it is about people signing a treaty, laying down their arms and changing government policy and institutions.

This is why it’s time to take on board the lessons of the past, and re-double our efforts to build a lasting peace that benefits all.