On World Refugee Day, consider the tragedy of Biblical proportions unfolding for 4 million refugees and 7.6 million persons displaced internally by the chaos in Syria — over half the country's population. This catastrophe is upending the ethnic, sectarian and political culture of Syria and its neighbors, and will provide fertile ground for tomorrow's crazies. The circumstances cry out for more effective action by the United States.

Syria's cataclysm has built itself on unrest, government brutality, and armed opposition to that brutality, which have broken down security and normal life there. In January 2013, less than two years after the first protests against President Bashar Assad, the official refugee tally reached 502,000. It tripled to 1.6 million in the following six months. Today's total, according to the U.N. High Commission for Refugees (UNHCR) is double that — 3.98 million. The actual number of refugees is likely 20 percent higher. Few will return.

Some live in camps run by the UNHCR, host governments or others. Better ones offer shipping-container housing and thriving market economies, but others are plastic sheeting shantytowns. Country by country, however, 70 to 90 percent live outside any camp or support network — in disused public buildings or destitute on the street. Two-thirds of Jordan's Syrian refugee population of 628,000 live below that country's poverty line, and one-sixth has to get by on less than $40 a month. The situation is little better elsewhere.

Children make up half the refugee population — figure 2 million, or about the same under-18 population as in Minnesota and Iowa combined. The UNHCR chief, Antonio Guterres, has warned the U.N. Security Council of a "lost generation," ill-schooled and, for the 100,000 already born abroad, stateless.

On top of Syria's refugees are some 7.6 million internally displaced by violence. Most of these have now moved three or more times. Half of these are children, too.

The destinations to which Syrians have fled are groaning.

In Lebanon, Syrian refugees total 1.2 million — one out of every five inhabitants of the country today; in Jordan, the figure is one in six. (A comparable influx from Mexico to the U.S. would total 82 million people.) A terrible burden financially, socially, and politically, these new populations will completely and likely permanently change the character of Jordan and Lebanon. Everywhere, refugees have swamped public health care and education services, lowered wages and raised the price of low-cost housing, causing resentment among the native citizenry. Syrians get blamed for a rise in crime.

Though it has absorbed more Syrians than any country, Turkey, with its larger population, is less awash. But people are not happy. In May, protesters' placards read, "We Don't Want Syrians." An influx of Kurds and developments in Syria's Kurdish north have sharpened the conflicts between Turks and Kurds in Turkey.

U.N. refugee commissioner Guterres called for "massive international support" for Syria's displaced. His agency has helped 1.8 million get access to food, drinking water and shelter. But its $11.3 billion 2015 budget for Syria has been only 22 percent funded. Since the U.N. cannot spend money it does not have, shortfalls have twice recently forced large-scale cuts in aid to Syrian refugees. Further cuts will come.

Action to address Syria's refugee catastrophe is a humanitarian and security necessity. Having given over $3 billion for Syrian refugee relief to date, the U.S. has been generous. We should do more, and we should be more persistent with other donors to step up to the plate.

Resettlement is inevitable. Europe already hosts over 250,000 Syrians. The State Department recently announced plans to accept 10,000 Syrians annually, a tiny step, but one that will be meaningful if sustained over time. The politics can be tricky: One presidential candidate expressed dismay at the idea of Syrian Muslims being allowed to come to the U.S. As a moral and humanitarian matter, that stance is wrong, and a generous American people should reject it.

We also need a more effective strategy on Syria. We should more energetically support U.N. efforts to negotiate local freezes in the fighting. We should give more political and practical support to the moderate Syrian opposition to complement arms and training programs. We should work with others to establish a no-fly zone over areas of Syria that can be secured by the Free Syrian Army — zones that will give the opposition something to fight for, augment its credibility within Syria and be a haven for those prepared to stay.

By acting prudently and cautiously, but also effectively, we can affect the situation for the better and show Syrians that we and the West, not ISIL, are the force for peace, security and freedom there and around the world.

Ross Wilson, a Minnesota International Center board director, served as U.S. ambassador to Turkey and Azerbaijan during a 30-year career in the U.S. Foreign Service.