A military exercise involving more than 11,000 troops from 19 countries is under way in Jordan, reportedly just miles from Syria's border.
Dubbed Eager Lion 2012, the operation is "very significant," a source close to the Jordanian government told NBC News, adding it was the first of its kind in 15 years "in terms of size and importance."
The source and an analyst both said the war games should be seen as a message to neighboring Syria's rulers.
Violence has raged in Syria for 14 months after mass protests turned into an insurrection against President Bashar al-Assad's rule. Assad's government has repeatedly accused foreign states of backing a "terrorist" campaign in Syria, an apparent reference to Gulf powers Saudi Arabia and Qatar which have argued that Syrian insurgents should be supplied with weapons.
A month-old truce brokered by international mediator Kofi Annan has failed to stop the violence, which has killed more than 9,000, according to U.N. figures. It has also caused a refugee crisis in the region.
Another source close to the government in Jordan told NBC News that while some of the exercises were being held near the Royal Jordanian Air Force's King Feisal Al Jafr airbase in the south, other exercises were under way near the Syrian and Iraqi borders in the east. The sources spoke to NBC News on condition of anonymity.
Experts in the region said the exercises were most certainly more than just building bridges between different countries.
"You can't honestly say that there is not a message when you get 19 nations together in multilateral force less than 50 miles away from the Syrian border," Michael Stephens of London-based military and security think tank RUSI told msnbc.com from Qatar.
"There is no possible reason as to why the Americans wouldn't want a joint operation held close to Syria," he added. "It enhances deterrence (and) the Americans could've quietened it down if they wanted to."
Media reports in Jordan claimed that the exercises were a message not only to Syria but Iran.
However, American and Jordanian military officials strenuously denied that there were operations taking place close to Syria.
"It's not about Syria, it's just a pure coincidence," U.S. Central Command Maj. Robert Bockholt told msnbc.com from Jordan. "Eager Lion 12 has been pre-planned."
The personnel from 19 nations -- Australia, Bahrain, Brunei, Egypt, France, Italy, Iraq, Jordan, Kingdom of Saudi Arabia, Kuwait, Lebanon, Pakistan, Qatar, Spain, Romania, Ukraine, United Arab Emirates, United Kingdom and United States -- were working together "to build functional capacity and enhance readiness," according to a statement from the combined operation, Task Force Spartan.
The exercise "does not target anyone -- none of the neighboring or world countries," Major Gen. Awni El-Edwan, Jordanian Armed Forces operations and training chief of staff, told journalists on Tuesday.
Reuters contributed to this report.
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