The Israeli military on Friday said one of the missiles broke up over Turkey, while the US said it was aware of the tests.
The Turkish military said apparent missile debris from Syria landed in two agricultural villages in the southern province of Hatay, causing no injuries or damage. It provided no information about the types of missile fired.
A Turkish Foreign Ministry official, speaking on condition of anonymity because ministry regulations bar him from identifying himself, said Syria has assured Turkey the incident was "just an accident" that occurred during routine military training.
White House spokesman Scott McClellan told reporters on Friday: "We're aware of the missiles that were launched, and I think I'll just leave it at that."
He made the comment in Crawford, Texas, where President George Bush is spending time at his ranch.
Syrian officials were not available for comment on Friday.
Israeli security officials, also speaking on condition of anonymity because the matter is so delicate, said it was Syria's first missile test since 2001.
They said they saw the launchings as a Syrian gesture of defiance to the United States and the United Nations, which pushed Syria to withdraw its troops from Lebanon after the February assassination of former Lebanese prime minister Rafiq al-Hariri, who favoured the pullout.
Israel, which captured the Golan Heights from Syria in the 1967 Mideast war, is concerned about Syria's missile programme, where Damascus is focusing its efforts against Israel's air superiority.
The Israeli security sources said the missiles launched last week included one older Scud B rocket, with a range of about 300km, and two Scud D's, with a range of about 700km.
All three missiles were launched from northern Syria, near Minakh, north of Aleppo.
The Turkish Foreign Ministry official said relations between the two neighbours were good and have been steadily improving. He pointed to a series of recent high-level visits between the two countries, including mutual visits by the countries' presidents.
Israeli security officials said this was the first time Syria had fired a missile over another country.