>> the war in syria has taken a dramatic turn as israel launched an air strike of its own inside syria over the weekend. they claim they wanted to take out weapons that might have been used by their enemies against them. while the israelis did not intend to become direct combatants in this civil war , these air strikes may now shift the debate in this country over what to do about this two-year-long conflict. our chief foreign correspondent richard engel is just across the syrian border in turkey tonight. richard, good evening.

>> reporter: good evening, brian. the u.s. is struggling to decide whether to get more involved. israel acted in secret without public debate and won't officially acknowledge it. it is a different way to have doing business . huge explosions lit up the sky over damascus. the target, sources say, advanced iranian-made missiles on their way to hezbollah . the anti- israel shiite militia that effectively runs lebanon. the missiles were taken out by american-made israeli f-16s, untouched by syrian air defenses. rebels tell nbc news syrian army forces were also attacked. the revolutionary guard. a blatant act of aggression, said syria . self-defense, said the white house .

>> the israelis justifiably have to guard against the transfer of advanced weaponry to terrorist organizations like hezbollah .

>> reporter: israel was on alert today, deploying anti-missile batteries and tanks near the syrian and lebanese borders. is israel trying to topple assad ? it says no. it wants to stop hezbollah from getting more weapons. it is difficult to know where the assad regime ends and hezbollah begins. last summer in syria , we traveled with rebels who attacked a government base. they discovered hezbollah flags and other paraphernalia, proof they said they were working together. now they are even closer and hezbollah says it won't let assad fall. a reminder that the war is now a regional conflict. the syrian government allied with hezbollah and iran. all shiites opposed by the rebels, turkey, qatar, saudi arabia and the uae, all sunni powers. then there is israel acting in its own interest while wanting no part in this regional religious war . secretary kerry is scheduled to meet russian president vladimir putin tomorrow. analysts say key to resolving the crisis is convincing putin personally to drop his support for assad . brian?

>> richard engel across the syrian border in turkey tonight. richard,