The mistrust among Syrians and between Syrians and the international community have been major stumbling blocks to ending hostilities and reaching a lasting political settlement. The United Nations has recently proposed a selective freeze of hostilities in Aleppo.

The intransigence of hard-liners on both sides of the conflict has thus far blocked political paths to resolving the conflict. Many international actors, including regional powers Saudi Arabia and Iran, continue to hold on to the delusion that a military solution is possible. The dire reality on the ground suggests otherwise. The battle lines between government and opposition forces remain frozen. Meanwhile, extremist forces such as the Islamic State in Iraq and the Levant and Jabhat Al-Nusra (the Nusra Front) have emerged as serious threats far beyond Syria. These forces will continue to thrive as long as large parts of Syria remain ungoverned.

The choices seem simple: All parties in Syria must take steps to show that they want peace, and regional and international actors must stop funding rival proxies.

The international community failed the Syrian people by arming rival groups and by failing to provide funds to address the catastrophic humanitarian consequences. The civilian population is paying for the folly of Syrian and international leaders. More than 9 million Syrians have been displaced, more than 200,000 have been killed, and at least 1 million have been injured. The influx of Syrian refugees has overwhelmed neighboring countries, especially Lebanon and Jordan.

As the fourth anniversary of the conflict in Syria approaches, there appears no end in sight. Horrendous violations of international law continue unabated. Syrians have allowed themselves to be used as proxies by self-interested foreign countries. The war has taken sectarian and criminal dimensions, drowning the reform agenda that spurred the popular anti-government protests in 2011.

“Our hope is that Aleppo could be a signal of goodwill, a confidence-building measure which could and can facilitate the restarting of a political process with a clear political horizon,” the U.N. envoy to Syria, Staffan de Mistura, said in January after a commitment from President Bashar al-Assad to stop airstrikes for six weeks. Armed rebel groups did not respond.

Foremost, the bombardment of civilian targets and the barrel bombs and artillery, mortar and rocket fire on populated areas must stop. All parties to this conflict must unilaterally — without any conditions — halt such indiscriminate bombardments. A freeze of general hostilities in Aleppo is a good start, but it should be extended to other cities.

Building confidence and trust among Syrians also entails the release of all political detainees and hostages by both sides. The international community must find the wisdom and the political will to respect two fundamental principles in the U.N. Charter: the inviolability of Syria’s territorial integrity and the sanctity of its sovereignty. This means stopping the flow of weapons, funds and fighters into Syria. The member states of the Security Council, Iran, Turkey and Saudi Arabia must respect such an injunction.

Only then can the Security Council demand the Syrian government and its opponents uphold international law. Otherwise, calls for a political solution in Syria will remain hollow. Most important, the international community must uphold the responsibility to protect civilians in all parts of the country without any discrimination.

Peace talks can be productive once these foundations are realized. But even then, all Syrians — across the political, sectarian and ethnic divides, both in Syria and in exile — must muster sufficient trust in one another to come together in a grand, inclusive national dialogue to determine the future of their country and its transition to peace. The road to peace will be long, and the road to reconciliation will be even longer.

In the meantime, Syrian civil society activists and professionals must continue to press for a political solution and develop a vision for Syria’s transition. Over the past 18 months, the Carter Center has brought some of these activists together to formulate fundamental principles that could serve as a foundation for a transition. The activists have proposed options for a transitional Syrian constitution.

Ultimately, the Syrians will have to decide the type of governance that a new constitution must support. Reforms and new leadership will have to be ordained through genuine popular votes once security and stability have been restored.