The Turkish and US governments are warning their citizens to avoid Syria.
The Turkish warning comes after two busloads of Turkish citizens were fired on by Syrian soldiers as they headed home from a pilgrimage to Saudi Arabia.
In a travel advisory, the US suggests Americans leave Syria immediately because the number of commercial airlines flying in and out of the country is falling and of those airlines still flying, many have reduced the number of flights.
Earlier, President Obama announced Washington's ambassador to Damascus would not be going back.
He was recalled in October after the US said threats had been made to his security.