By Natalia Antelava
BBC News, Beirut
Syrian troops established camps on 22 September overlooking Lebanon's border
Since the 2006 war between Israel and Hezbollah, the US has provided an estimated $400m (£228m) in military assistance to the Lebanese army, and now Washington is promising more aid.
The US has said it will provide Lebanon with millions of dollars worth of ammunition, military vehicles and helicopters.
On Monday, Lebanese Defence Minister Elias Murr and US Assistant Secretary of Defence for International Security Affairs Mary Beth Long inaugurated a special bilateral commission that will oversee military relations between the two countries.
The move follows the first visit by Lebanese President Michel Suleiman to Washington, and comes at a time when the US has expressed concern about Syrian military build-up on the Lebanese border.
"This is an unambiguous message to Syria that any intervention into Lebanon will not be tolerated," says Hilal Khashan, the head of the political science department at the American University in Beirut.
Analysts say that one of the goals of US aid to the Lebanese army is to undermine the military might of the pro-Syrian political and military movement, Hezbollah.
But Hezbollah, which Washington calls a terrorist organisation, is now part of Lebanon's government - and its leader, Hassan Nasrallah, opposes co-operation with the US military.
On Tuesday, the pro-Hezbollah media downplayed the importance of American aid to the Lebanese army.
A report on the al-Manar television station said the aid, as well as visits by the US officials, were nothing but "lip-service and rubber political cheques" by a US administration that was on its way out.
However, US military aid has proved an important factor in the past, and particularly during the past year's clashes between Lebanese soldiers and Islamic militants in Nahr al-Bared Palestinian refugee camp in the north of the country.
It took the army three months to crush an uprising there, but troubles in the north seem far from over.
Hassan Nassrallah told supporters Lebanon should not ask for US help
In the past two months, 25 people, most of them soldiers, were killed in two car bomb attacks in the northern city of Tripoli. The government said Islamic militants were behind the blasts.
After the most recent explosion, Syria said it saw Lebanon as a threat to its security and accused the Lebanese army of not doing enough to fight the Islamic militants.
But while Damascus talks about its fears of terrorism, Prof Khashan says the attacks could play to Syria's political interests.
"Syrians want to show that the Lebanese army cannot defend itself, that no matter how much money [the Americans] give to the Lebanese Army, it will be a waste and that only Syrian military presence can bring order to Lebanon," he says.
Following almost 30 years of Syrian military presence in Lebanon, which ended in 2005, the prospect of another Syrian intervention has been looming large in Lebanon's turbulent political circles.
Thousands of Syrian troops have deployed on the Lebanese border, and fears of an invasion seem to be gaining new strength among anti-Syrian politicians and their supporters.
For its part Damascus, and its allies in Lebanon, say the troops have been deployed to combat smuggling.
Many analysts say the truth may lie somewhere in between.
Damascus maybe flexing its muscles, they explain, but invasion is not on President Bashar al-Assad's agenda, if only because of the damage it could do to Syria's image overseas.
Mr Assad wants closer relations with the West and he seems serious about the new Turkish-mediated talks with Israel. An invasion could undermine all of these efforts.
But Washington seems to side with the opinion of anti-Syrian politicians in Lebanon, who say that Damascus is simply waiting for an opportunity to invade under the pretext of dealing with Sunni extremists in the north.
As the US and Lebanon agreed to set up their new military commission, Washington also warned Damascus against any possible military intervention in Lebanon.