BEIRUT — The French parliament will debate Wednesday whether the nation should launch strikes against Syria, though France's president says he will wait for a decision from the U.S. Congress on possible military action against Bashar Assad's regime.

As the Obama administration worked to build support ahead of the Congress vote, the U.S. and Israel conducted a joint missile test Tuesday in the eastern Mediterranean in an apparent signal of military readiness. In the operation, a missile was fired from the sea toward the Israeli coast to test the tracking by the country's missile defense system.

The French parliament will debate the Syria issue Wednesday, but no vote is scheduled. France's constitution doesn't require such a vote for military intervention unless its lasts longer than four months, though some French lawmakers have urged President Francois Hollande to call one anyway.

The U.S. and France accuse the Syrian government of using chemical weapons in an Aug. 21 attack on rebel-held suburbs of Damascus that killed hundreds of people. President Barack Obama and Hollande are pushing for a military response to punish Assad for his alleged use of poison gas against civilians — though U.S. officials say any action will be limited in scope, not aimed at helping to remove Assad.

Obama appeared on the verge of launching missile strikes before abruptly announcing on Saturday that he would first seek congressional approval. Congress returns from its summer recess next week.

On Tuesday, the White House won backing for military action from two powerful Republicans — House of Representatives Speaker John Boehner and House majority leader Eric Cantor.

In Paris, Hollande said that the U.S. vote "will have consequences on the coalition that we will have to create." He did not specify whether that meant a military coalition.

"A large coalition must therefore be created on the international scale, with the United States — which will soon take its decision — [and] with Europe . . . and Arab countries," Hollande said.

If Congress votes no, France "will take up its responsibilities by supporting the democratic opposition [in Syria] in such a way that a response is provided," he added.

France's government on Monday released an extract of intelligence gathered by two leading French intelligence agencies alleging that Assad's regime was behind the attack and at least two other, smaller-scale ones earlier this year.

Hollande added Tuesday that France had indications the nerve agent sarin was used in the Aug. 21 attack, a claim U.S. officials have also made.

The United States and France say the alleged chemical attack violates international conventions. Russia, which with Iran has been a staunch backer of Assad throughout the conflict, has brushed aside Western evidence of an alleged Syrian regime role.

At the United Nations, Secretary-General Ban Ki-moon warned that any "punitive" action could unleash more turmoil and bloodshed in that nation's civil war.

"I take note of the argument for action to prevent a future use of chemical weapons. At the same time, we must consider the impact of any punitive measure on efforts to prevent further bloodshed and facilitate the political resolution of the conflict," Ban said.

With the Middle East anxious as it awaits a decision about strikes, Israel and the U.S. tested the Jewish state's Arrow 3 missile-defense system over the Mediterranean.

A medium-range decoy missile, known as a Sparrow, was fired in the Mediterranean, and the system successfully detected and tracked it, the Israeli Defense Ministry said. The decoy was not carrying a warhead and the system did not intercept it, the ministry said.

In a statement Tuesday, Pentagon spokesman George Little said the U.S. provided technical assistance and support to the Israeli test.

He said the test was "long planned to help evaluate the Arrow Ballistic Missile Defense system's ability to detect, track, and communicate information about a simulated threat to Israel."

He said the test had nothing to do with the U.S. consideration of military action in Syria.

Nonetheless, it served as a reminder to Syria and its patron, Iran, that Israel is pressing forward with development of a "multilayered" missile-defense system. Both Syria and Iran, and their Lebanese ally Hezbollah, possess vast arsenals of rockets and missiles.

The Arrow 3, expected to be operational around 2016, would be the first such "multilayer" missile-defense system, designed to intercept long-range missiles such the Iranian Shahab before they re-enter the atmosphere.

Last year, Israel also successfully tested a system designed to intercept missiles with ranges of up to 300 kilometers (180 miles) which is expected to be operational by early 2015.

Another system for short-range rockets successfully shot down hundreds fired from the Gaza Strip during eight days of fighting in November, and more recently intercepted a rocket fired from Lebanon.

Meanwhile in Syria, regime troops recaptured the town of Ariha, a busy commercial center in the restive northern province of Idlib following days of heavy bombardment, according to the Britain-based Syrian Observatory for Human Rights.

Ariha has changed hands several times in the past two years. Rebels had succeeded in wrestling it from government control late last month.

Since the outbreak of the Syria conflict in March 2011, the two sides have fought to a stalemate, though the Assad regime has retaken the offensive in recent months. Rebel fighters control large rural stretches in northern and eastern Syria, while Assad is holding on to most of the main urban areas.

The Syrian conflict, which began as a popular uprising against Assad in March 2011, later degenerated into a civil war that has killed more than 100,000 people.

The U.N. refugee agency announced Tuesday that the number of Syrians who have fled the country has surpassed the 2 million mark.

Along with more than four million people displaced inside Syria, this means more than six million Syrians have been uprooted, out of an estimated population of 23 million.

Antonio Guterres, the head of the Office for the U.N. High Commissioner for Refugees, said Syria is hemorrhaging an average of almost 5,000 citizens a day across its borders, many of them with little more than the clothes they are wearing. Nearly 1.8 million refugees have fled in the past 12 months alone, he said.

The agency's special envoy, actress Angelina Jolie, said "some neighboring countries could be brought to the point of collapse" if the situation keeps deteriorating at its current pace. Most Syrian refugees have fled to Jordan, Lebanon, and Turkey.