Syria's civil war is back in the spotlight this week: Most notably, Sen. John McCain (R-Ariz.) made a surprise visit to rebel leaders on Monday, and Russia and the U.S. have stepped up their efforts to hold peace talks in Geneva next month. The Syrian government has reportedly agreed to participate, although leaders of the opposition Syrian National Coalition, sharply divided by internal squabbling, can't agree on whether to attend.

Despite this renewed push to bring the two-year conflict to a close, signs are mounting that the war is actually spreading. Here, five indications that the conflict is spilling over Syria's borders:

1. The E.U. lifts a ban on arming rebels
The biggest new development came Monday night when European Union foreign ministers agreed, at the urging of Britain and France, not to renew a ban on delivering weapons to rebels fighting to topple Syrian President Bashar al-Assad's regime. "While the lifting of the E.U. arms embargo is theoretically good news for the fractious Syrian opposition," says Jim Muir at BBC News, "it is clearly going to be some time before it has any effect on the battlefield balance." The move is meant to send a signal to Assad to leave, but that's wishful thinking, Muir says, as he's made it clear he's fighting to the end.

As the Syrian conflict deepens, the stakes are clearly getting higher by the day. But for the rebels at least the eventual possibility of carefully controlled arms deliveries is there, in what looks like [is going to be] a bloody, long-haul struggle. [BBC News]

2. Russia sends Assad sophisticated missiles
Russia, Assad's most powerful defender, vowed to counter the E.U. by following through with plans to arm Assad with state-of-the art, long-range S-300 air defense missiles. Russia didn't disguise that it was responding to the E.U. move, which it clearly sees as an indication that the U.S. and its E.U. allies are moving toward more directly aiding the rebels, maybe even by setting up a naval blockade or no-fly zone. Deputy Foreign Minister Sergei Ryabkov said Moscow was giving Assad greater firepower to "restrain some 'hot heads' considering a scenario to give an international dimension to this conflict."

3. Israel vows to take out the Russian arms
The Russian power play prompted Israel, which has already bombed targets inside Syria, to delve even deeper into the conflict. Israeli Defense Minister Moshe Yaalon said that the Russian missile systems, which had not left Russia yet, would amount to an unacceptable boost in the arsenal of its troubled neighbor. "I hope they will not leave, and if, God forbid, they reach Syria, we will know what to do," he said.

4. Lebanon's Hezbollah jumps in on Assad's side
Syria's conflict also appears to be crossing the border into another next-door nation, Lebanon. Four rockets rained on the Lebanese town of Hermel, on the Syrian border, Tuesday, badly injuring a woman who was sitting under an olive tree in her yard. The attack came shortly after three Lebanese soldiers were shot dead in an attack on a border crossing.

Locals said they believed they had been targeted by Syrian rebels or Lebanese Sunni Muslim sympathizers to retaliate after Hassan Nasrallah, leader of the Lebanese militant group Hezbollah, declared on Saturday that his group would go all out to keep the opposition from toppling Assad. "It is our battle, and we are up to it," Nasrallah said, days after Hezbollah militants began openly fighting alongside Syrian army troops trying to retake Qusair, a strategic rebel stronghold.

These events are only increasing pressure on the U.S. and its allies to get involved. Eliott Abrams of the Council on Foreign Relations says that Hezbollah's open and active backing of Assad shows that Hezbollah and its fellow-Shiite patrons in Iran have already made this civil war into a regional conflict. They're committed to winning, Abrams says. "If the United States allows this to happen, allows Hezbollah and Iran to win, our own credibility will have been shredded — with significant consequences throughout the world. It can only be hoped that Nasrallah's clarity and his contempt for us will somehow awaken in the Obama administration an understanding of American interests and the need to defend them."

5. Evidence of Syria's alleged use of chemical weapons could force the world to do something
The United Nations reported last month that it was pretty certain that chemical weapons had been used in Syria. Now reporters from the French daily Le Monde say they have compiled more evidence that the regime, which is believed to have a massive stockpile of undeclared chemical agents, has been using poison gases on the opposition. Le Monde says it has samples of weapons used by Assad's troops, and it's testing them now. President Obama has declared the use of these prohibited weapons a "red line" that could justify greater foreign intervention — if Le Monde has definitive proof, calls for the U.S. and its allies to jump in to help the rebels will only grow louder.