The State Department secretly accused Syria of not living up to its promise to top U.S. diplomats to stop supplying Lebanon's militant Hezbollah group with missiles.
As a result, the group has enough firepower to threaten turning any clash with Israel into a regional war, The New York Times reported on its website Monday evening.
The disclosure comes from the trove of secret State Department cables released to a number of news outlets by the document-dumping website WikiLeaks.
Syrian President Bashar al-Assad told a high-ranking American diplomat that his government stopped sending weapons to Hezbollah, an assurance the State Department questioned a week later, the Times reported.
"In our meetings last week it was stated that Syria is not transferring any 'new' missiles to Lebanese Hizballah," Secretary of State Hillary Clinton wrote with an alternative spelling for the group in a February cable. "We are aware, however, of current Syrian efforts to supply Hizballah with ballistic missiles. I must stress that this activity is of deep concern to my government, and we strongly caution you against such a serious escalation."
The Times cites a Pentagon official saying the militant group's armory has as many as 50,000 rockets and missiles, including 40 missiles capable of reaching the Israeli capital of Tel Aviv.
The Times report provides a look at what the U.S. knows about the flow of illegal arms into the Middle East.
For example, Hamas, the militant group in Gaza, and Hezbollah receive North Korean missile technology through Iran and Syria, the Times reported.
Hamas also receives weapons from Iran through the Sudanese capital of Khartoum, the Times reported. Diplomats allege in the cables that the weapons are flown from Tehran on huge cargo planes operated by Sudan's Badr Airlines. The Sudanese government said the planes were carrying farm equipment, the Times reported.
More on WikiLeaks
WikiLeaks: Assange Arranging Police Interview
Swiss Cut Off WikiLeaks' Bank Account
WikiLeaks' Swedish Servers May Be Under Attack
Video: Julian Assange's Life on the Run
WikiLeaks' Assange May Seek Swiss Asylum
State Dept. Denies WikiLeaks Warning to Columbia
WikiLeaks: World Leaders Are Real People, Too
Iran Official: U.S. Fabricated WikiLeaks Cables
Afghan Minister: WikiLeaks Hurt U.S.-Afghan Ties
Video: Army Pvt. Claims Responsibility for WikiLeaks Spill