A joint U.S.-Israeli missile test on Tuesday in the eastern Mediterranean Sea triggered Russian radars in what leaders described as a "routine" exercise.
Both U.S. and Israeli defense officials insisted that the test firing of a Sparrow missile was routine and unrelated to the Syrian crisis. However, the announcement of the test came only after Moscow complained that its radars had picked up two "ballistic objects" fired in the general direction of the Syrian coast.
"This test had nothing to do with United States' consideration of military action to respond to Syria's chemical weapons attack," Pentagon Press Secretary George Little said in a statement.
The U.S. has five destroyers in the Mediterranean Sea armed with Tomahawk Land Attack Missiles, which many expect to be used in any attack on Syria.
Russia has maintained a naval presence of about four warships in the eastern Mediterranean during the course of Syria's civil war, according to Russian news agencies.
On Sunday, the Interfax news agency said that that Russian intelligence and reconnaissance ship Priazovye had left the Black Sea port of Sevastapol enroute to the eastern Mediterannean .
The Priazovye would operate separately from other Russian ships on station, and its mission would be "to gather current information in the area of the escalating conflict," Interfax said.
The U.S. had provided technical assistance and support to the Israeli Missile Defense Organization flight test of a Sparrow target missile that was tracked in central Israel by the Arrow Ballistic Missile Defense System, Little said.
Military analysts said the test could also serve other purposes. It is sending a message to Damascus that U.S. ships carrying Tomahawk cruise missiles were still off the coast awaiting Congressional authorization to strike, said Lawrence Korb, a former assistant secretary of Defense.
U.S. commanders could also have been seeking to pick up intelligence from the reaction of Syrian radars, said Korb, now an analyst with the Center for American Progress.
Russian news agencies said Defense Minister Sergei Shoigu reported the test firing to President Vladimir Putin, who will attend an economic summit later this week with President Obama in St. Petersburg, Russia.
"The trajectory of the targets in question was from the central part of the Mediterranean Sea towards the eastern part of the Mediterranean coastline," the Interfax news agency quoted the Russian defense ministry as saying.
Russia had reported two "ballistic objects" but the Israeli statement mentioned only one Sparrow.
Israeli Defense Minister Moshe Ya'alon later echoed the Pentagon statements that the test was planned a long time ago and was not related to events in Syria.
"We aren't getting involved in what is happening in Syria. What happened there crossed a red line from the Americans' perspective, but we aren't supporting, or involved in, a possible strike," Ya'alon said, the Jerusalem Post reported.
The test firing came amid a U.S. naval buildup in the region to carry out President Obama's decision to strike Syria for its alleged use of chemical weapons – if Congress votes to authorize the attacks.
The civil war in Syria has now forced more than two million refugees to flee the country to neighboring states, the United Nations reported Tuesday. More than 3 million Syrian refugees are expected by the end of the year, said UN High Commissioner for Refugees Antonio Guterres.
"At this particular moment it's the highest number of displaced people anywhere in the world," Guterres said at a press briefing in Geneva. "Syria has become the great tragedy of this century -- a disgraceful humanitarian calamity with suffering and displacement unparalleled in recent history."
More than 500,000 of the refugees are in sprawling camps in Jordan, where the U.S. has more than 1,000 troops on the ground along with several F-16 fighters and Patriot missile batteries. Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, visited the camps in Jordan last month and said U.S. troops were helping with camp sanitation systems.
As of the end of August, the agency counted 716,000 refugees in Lebanon, 515,000 in Jordan, 460,000 in Turkey, 168,000 in Iraq and 110,000 in Egypt.
