Both sides signaled they do not want to escalate an incident that has the potential to explode into a regional conflict, but the downing of the Turkish reconnaissance plane on Friday was a dramatic sign that the violence gripping Syria increasingly is spreading outside its borders.
Tensions already were high between Syria and NATO-member Turkey. The neighbors used to be allies before the Syrian revolt began in March 2011, but Turkey has become one of the strongest critics of the Syrian regime's brutal response to the country's uprising and is playing host to civilian and military Syrian opposition groups.
Germany and Iraq urged Turkey and Syria to remain calm and not let the unrest in Syria become a wider conflict in the area.
In a telephone interview with Turkish TV news channel A Haber on Saturday, Syrian Foreign Ministry spokesman Jihad Makdissi said the downing of Turkey's F-4 plane was an "accident, not an attack."
"An unidentified object entered our air space and unfortunately as a result it was brought down. It was understood only later that it was a Turkish plane," A Haber quoted Makdissi as saying in a translation of the interview. "There was no hostile act against Turkey whatsoever. It was just an act of defense for our sovereignty."
The plane went down in the Mediterranean Sea near Syria, and its two Turkish pilots remain missing.
"What is important now is that Turkey and Syria are working together to find the pilots," Makdissi said.
Turkish President Abdullah Gul and other officials said Saturday that their government is trying to assess the exact circumstances of the incident and would take unspecified retaliatory steps accordingly. Gul conceded that Turkish aircraft may have unintentionally violated Syrian airspace.
It was not clear if Turkey was contemplating military retaliation, increased sanctions, or other possible steps, including demands for compensation or an apology. But Faruk Celik, the Turkish Labor and Social Security Minister, said his nation would retaliate "either in the diplomatic field or give other types of response."
"Even if we assume that there was a violation of Syria's airspace — though the situation is still not clear — the Syrian response cannot be to bring down the plane," Celik told reporters. "The incident is unacceptable. Turkey cannot endure it in silence."
Turkey has joined nations such as the United States in saying that Syrian President Bashar Assad should step down because of the uprising in his country that has killed thousands of people. Turkey also has set up refugee camps on its border for more than 32,000 Syrians who have fled the fighting.
Turkey said after an April border shooting incident — in which two people in a Turkish refugee camp died— that it would call on its NATO allies to intervene should it feel its security was being threatened.
Turkish Foreign Minister Ahmet Davutoglu met with military officials Saturday to assess what steps to take and to coordinate the search and rescue operation for the two missing pilots and the plane's wreckage, the Foreign Ministry said. The minister also met with Erdogan, but there was no announcement made after either of the meetings.
A Turkish official familiar with the meeting said Turkey was examining the plane's radar route and other flight data to ascertain whether the aircraft was flying over Syrian territory when it was shot down. The official spoke on condition of anonymity because he was not authorized to brief journalists and would provide no further details.
On Friday, Syria said its forces shot down a Turkish military plane that had entered its airspace. The plane, an unarmed F-4, went down in the Mediterranean Sea about 8 miles (13 kilometers) from the Syrian town of Latakia, Turkey said.
In Baghdad, Iraqi Foreign Minister Hoshyar Zebari said Saturday that the recent defection of a Syrian pilot to Jordan and the downing of the Turkish jet showed that the Syrian conflict could have far-reaching repercussions.
"Our main concern is the spillover of the crisis into neighborhood countries. No country is immune from this spillover," he said. "If this conflict were to turn into all-out sectarian or civil war, Iraq would be affected, Lebanon would be affected, Jordan would not be immune, (and) Turkey could be (affected)."
German Foreign Minister Guido Westerwelle said he was "greatly worried" by the incident, urged a thorough investigation and welcomed Turkey's cool-headed reaction in the incident's immediate aftermath.
U.N. Secretary-General Ban Ki-moon was following the situation closely and hoped the incident would be "handled with restraint by both sides through diplomatic channels," a spokesman said.
The Turkish government said the aircraft was a reconnaissance plane, not a fighter jet. Gul said it is "routine" for such jets flying at high-speeds to unintentionally violate other countries' air spaces for short periods of time. "Was that the case, or did (the incident) occur in our own air space? These facts will emerge," he said.
Syria claimed the jet violated its air space over territorial waters, penetrating about 1 kilometer (0.62 mile). It said Syrian forces only realized it was a Turkish jet after firing at it.
Turkish Deputy Prime Minister Bulent Arinc and other government ministers urged restraint. "We must remain calm and collected," he said. "We must not give premium to any provocative speeches and acts."
The leader of Turkey's main opposition party, Kemal Kilicdaroglu, said the downing of the plane was unacceptable, but he also urged calm.
"All diplomatic channels must be kept open. We are expecting a coolheaded assessment of the incident," he said.