According to Russia Today, Green made the statements in a ceremony at Center for International and Strategic Research marking World Day of Humanitarian Aid.
Noting that the 13 million make up 80 percent of the Syrian inhabitants, he said that today, Syria faces one of the most complicated human crises in the world.
Earlier, UN in a report said financial damages to the Syrian infrastructure in the wake of the seven-year war exceed 388 billion dollars.
Syria war which started in 2017 has so far claimed over 350,000 lives and displaced over half of its population.
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