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Israel airstrikes loom over US diplomacy in Syria

Kerry in Russia for talks with Assad’s key ally

Israeli tanks conducted military training near the Syrian border in the Golan Heights on Monday after Israeli airstrikes reportedly hit a military research center near Damascus.

ATEF SAFADI/EPA

Israeli tanks conducted military training near the Syrian border in the Golan Heights on Monday after Israeli airstrikes reportedly hit a military research center near Damascus.

WASHINGTON — Israel’s willingness to hit Syrian targets it sees as threats has complicated the Obama administration’s internal debate about arming President Bashar Assad’s foes and may change the way the United States approaches allies as it tries to boost the rebels, including with possible military aid.

As Secretary of State John Kerry flew to Russia on Monday for talks with the Assad regime’s most powerful ally, the administration remained tight-lipped on both Israel’s weekend airstrikes and their implications for Washington decision-making.

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Israeli warplanes reportedly targeted caches of Iranian missiles that were bound for Hezbollah, the Lebanon-based terror group that has threatened Israel. The weapons would have allowed Hezbollah to strike Tel Aviv and as far as southern Israel from inside Lebanon.

Still, Israel’s actions put Damascus and Moscow on notice that the United States and its allies may not wait for an international green light to become more actively engaged. The administration said last week it was rethinking its opposition to arming the rebels or taking other aggressive steps to turn the tide of the two-year-old civil war toward the rebels.

At the same time, Israeli involvement in the war carries risks. Instead of prodding Russia into calling for Assad’s ouster, it could bring Arab sympathy for Assad and prompt deeper involvement from Iran and the Lebanese militant group Hezbollah, actors committed as much to preserving Assad as to fighting the Jewish state.

Although Israel has not officially acknowledged it carried out the airstrikes, Syrian officials on Monday blamed Israel, calling it a ‘‘declaration of war’’ that would cause the Jewish state to ‘‘suffer.’’

Russia, alongside China, has blocked US-led efforts three times at the United Nations to pressure Assad into stepping down. Officials said Kerry hopes to change Moscow’s thinking with two new arguments: US threats to arm the Syrian rebels and evidence of chemical weapon attacks by the Assad regime.

Kerry, US officials said, hopes that may be enough to persuade Russian President Vladimir Putin to support, or at least not veto, a fresh effort to impose UN sanctions on Syria if Assad does not begin transition talks with the opposition. The officials demanded anonymity because they were not authorized to speak publicly about the confidential talks.

US officials said the administration does not think the weekend activity will force President Obama’s hand, noting that the US administration’s main concern is the use of chemical weapons by Assad, while Israel’s top concern is conventional weapons falling into the hands of its foes.

The chemical weapons argument is now under surprising attack, with former war crimes prosecutor Carla Del Ponte saying she and fellow members of a four-member UN human rights panel have indications the nerve agent sarin was used by Syrian rebel forces but not by government forces.

Despite a clarification from the United Nations that it has not yet made any definitive determination on chemical weapons use, Washington pushed back on Del Ponte’s assertion, saying it is highly likely that the Assad regime, and not the rebels, has been behind any chemical weapons use.

‘‘We are highly skeptical of suggestions that the opposition could have or did use chemical weapons,’’ White House spokesman Jay Carney said.

The State Department said the administration continues to believe that Syria’s large chemical weapons stockpiles remain securely in the regime’s control.

The Obama administration opened the door to new military options in Syria after declaring last week it strongly believed the Assad regime used chemical weapons in two small-scale attacks in March. Two days after that announcement, Defense Secretary Chuck Hagel said arming the Syrian rebels was a consideration.

Before departing for Russia, Kerry visited the Pentagon for a lunch meeting with Hagel.

There are several options for escalation of US involvement, from arming the rebels to targeted airstrikes and imposing no-fly zones. However, arming the rebels is the most likely option, officials said.

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