As the Syrian military continues to advance against rebel fighter strongholds in Aleppo and its surrounding suburbs Wednesday, several high level diplomats defected, adding to the long list of officials who have abandoned President Bashar Assad's struggling regime.

The Syrian diplomats, one from the United Arab Emirates and the other from Cyprus, deserted their posts like other senior Syrian officials have since the uprising began. U.S. officials and analysts say it is one of the strongest signs that Assad is losing his grip on power.

Jim Phillips, a senior analyst with the Heritage Foundation, said Assad's army and government "is hemorrhaging with deserters" and those losses will continue to strengthen the rebel fighting forces, he said.

However, he warned, "a negotiated transition is increasingly unlikely and rebels may not have strength to finish off Assad quickly but will grind down his supporters in an ugly dogfight," he said.

The fighting in Syria has already claimed an estimated 17,000 lives, a number that could rise rapidly as fighting escalates. Activists and military defectors with the Free Syrian Army are pleading with the international community for intervention, humanitarian supplies and weapons.

"A long, drawn out fight will present a number of problems for the international community," said a U.S. official with knowledge of the region. "Concern over chemical and biological stockpile security is just one of those major concerns -- the quicker Assad's regime falls the better it will be for everyone."

Syrian officials threatened this week to use chemical weapons against any foreign intervention but said they would not be used against its citizens. U.S. officials are concerned that those weapons will land in the hands of extremist groups, like al Qaeda, now operating inside Syria.

The Syrian Observatory for Human Rights, an opposition group, said Wednesday that more than 40 people have been killed across Syria in the past 24 hours.

"Activists inside the city of Altal, a Damascus suburb, reported an extensive attack by Assad over the city," said Sawsan Jabri, spokeswoman for the Syrian Expatriates Organization.

Violence in Aleppo continued to escalate since Tuesday, when the Syrian military bombed the rebels with fighter jets. Rebels are sending in reinforcements and holding off the Syrian army, which has entered the city with weapons and tanks, activists in Syria told The Washington Examiner.

"We are expecting a big attack on Aleppo," local activist Mohammed Saeed said via Skype to the Associated Press. He said some 80 tanks had been spotted in the countryside being hauled by flatbed trucks toward the city. "People are worried they might be hit by random shelling and are fleeing."

Turkish officials said they sealed their border to trade with Syria, worth $3 billion but said they would allow other areas to remain open for civilians fleeing the violence or in search of supplies, according to the Associated Press.

Assad, whose family belongs to the minority Alawite tribe, has reportedly fled to the coastal city of Latakia in the Alawite heartland.

Phillips said Assad could ask for asylum in Russia if the situation continues to deteriorate in Syria. "But he may be betting that the opposition will fracture and fall apart before it can dig him out of Alawite mountain strongholds," he said.

Sara A. Carter is The Washington Examiner's national security correspondent. She can be reached at