KUWAIT — Aid groups tackling the humanitarian catastrophe in Syria said they were disappointed that only $3.8 billion of a requested $8.4 billion had been pledged at a U.N. summit in Kuwait.

Nearly 80 governments and dozens of aid agencies attended Tuesday’s meeting, at which the United States promised $507 million, Kuwait $500 million, the United Arab Emirates $100 million and Saudi Arabia $60 million.

Some 200,000 people have died and nearly half the Syrian population has been displaced by the turmoil that began with anti-government protests in 2011 and escalated into full-scale civil war.

The United Nations was appealing for cash to help 18 million people, including Syrians inside and outside Syria and people in neighboring countries struggling to support Syrian refugees.

“We are disappointed, it’s fair to say,” said Caroline Anning, a spokeswoman for Save The Children. “The needs are increasing, and the amount being pledged is decreasing.”

Andy Baker, who manages Oxfam’s response to the Syria crisis, was also disappointed. “We always thought that $8.4 billion was a very optimistic appeal, but it’s sad to see we’re not even halfway there,” he told the Thomson Reuters Foundation.

Although the response at the first annual conference in Kuwait in 2013 exceeded the $1.5 billion requested, last year’s conference secured pledges of only $2.4 billion towards a $6.5 billion appeal. But not all the pledged funding arrived.