Updated

JERUSALEM—Syria has transferred long-range Scud missiles to the Lebanese Shiite militant group Hezbollah, Israeli and U.S. officials alleged, in a move that threatens to alter the Middle East's military balance and sets back a major diplomatic outreach effort to Damascus by the Obama administration.

Israeli President Shimon Peres on Tuesday publicly charged President Bashar Assad's government with transferring Scud missiles to Hezbollah's forces inside Lebanon. Syria and Hezbollah both denied the charges. But the allegations already are affecting U.S. foreign policy: Republicans pressed on Capitol Hill to block the appointment of a new American ambassador to Damascus, according to congressional officials. The White House said it was pressing ahead.

The Scuds are believed to have a range of more than 435 miles—placing Jerusalem, Tel Aviv and Israel's nuclear installations all within range of Hezbollah's military forces. During a monthlong war with Israel in 2006, Hezbollah used rockets with ranges of 20 to 60 miles.

Israeli officials called Scud missiles "game-changing" armaments that mark a new escalation in the Mideast conflict. They alleged that Mr. Assad is increasingly linking Syria's military command with those of Hezbollah and Iran.

Officials briefed on the intelligence said Israeli and American officials believe Syria transferred Scud missiles built with either North Korean or Russian technology.

Rumors of the arms transfer had been swirling around Jerusalem and Washington for more than a week, but both Israeli and U.S. officials initially declined to confirm the reports. "Syria claims it wants peace while at the same time it delivers Scuds to Hezbollah, whose only goal is to threaten the state of Israel," Peres said in an interview with Israeli radio.

President Barack Obama has made engaging Assad's government a cornerstone of his Mideast policy, hoping to woo Damascus into a regional peace process and lure it from a strategic alliance with Iran.

Continue reading at The Wall Street Journal