U.S. calls for Syrian military to defect

Damage and destruction litter a street in the battered city of Qusayr, southwest of Homs, in western Syria, on June 20.

• At least two people are killed in new attacks in Aleppo and Homs, opposition says
• The opposition armed group says it needs weapons to battle the regime
• Syrian opposition spokesman says calling for the defections is not enough

(CNN) -- Government forces shelled northern Syria with helicopters Saturday, opposition activists said, a day after U.S. officials reiterated calls for the troops to break ties with the regime.

At least two people died in the attacks in Aleppo and Homs, the Local Coordination Committees said

The new attacks come the same week U.S. officials applauded the defection of four senior Syrian military officers to the opposition, calling it another sign that the government of President Bashar al-Assad is weakening.

Jordan granted a Syrian pilot asylum Thursday after he landed his military jet in the neighboring country and announced his defection.

"We have had four senior army officers -- two brigadier generals and two colonels -- defect yesterday and join the opposition," State Department spokeswoman Victoria Nuland said Friday.

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"We have been calling for many, many weeks for members of the military ... to refuse orders and to refuse to participate in the violence that's ongoing. So we are beginning to see this stream accelerate, and that's a good thing."

The U.S. ambassador to Syria, Robert Ford, this week also urged military members to "reconsider their support" for the regime, saying it is losing the battle.

But a leader of the Syrian opposition fighters said calling for the defections is not enough.

"We appreciate the U.S .call for more defection but we need to keep the world in mind that every Syrian civilian or soldier is under constant threat and everyone who dares to challenge the regime may get killed on the spot," said Lt. Riad Ahmed, a spokesman for the Free Syrian Army, an armed opposition group.

Ahmed, who is based in Turkey, said fighters battling the government forces are at a disadvantage.

"We in the Free Syrian Army need weapons so we can fight back in order to topple this sadistic regime. Some smugglers may manage to get us few light weapons, but we need military help so we can fight and win this revolution."

The international community has pinned its hopes of ending the 15 months of bloodshed to a peace plan put forth by Kofi Annan, the special envoy to Syria for the Arab League. But that has failed to achieve results.

Since the anti-government uprising started in March last year, violence has killed more than 15,000 people in Syria, mostly civilians, according to the Syrian Observatory for Human Rights. The United Nations has said that at least 10,000 people have been killed in the conflict.

Opposition groups say the violence began when a government crackdown on peaceful protesters generated a nationwide uprising.

Annan urged countries to use their pull on the combatants to stop the fighting.

"It is time for countries of influence to raise the level of pressure on the parties on the ground and to persuade them that it is in their interest to stop the killing and start talking," Annan said in Geneva, Switzerland.

"... If our efforts are to succeed, we shall need the united and sustained support of the international community. This is essential."

Syria consistently blames terrorists for the violence.

CNN cannot confirm specific reports of violence in Syria because the government has restricted access to the country by international journalists.

CNN's Saad Abedine and Jamie Crawford contributed to this report.