BEIRUT - Syrian tanks and troops massed Monday outside the resistance stronghold of Homs for a possible ground assault that one activist warned could unleash a new round of fierce and bloody urban combat even as the Red Cross tried to broker a cease-fire to allow emergency aid in.
A flood of military reinforcements has been a prelude to previous offensives by President Bashar Assad's regime, which has tried to use its overwhelming firepower to crush an opposition that has been bolstered by defecting soldiers and hardened by 11 months of street battles.
"The human loss is going to be huge if they retake Baba Amr," said Rami Abdul-Rahman, who heads the Britain-based activist group Syrian Observatory for Human Rights.
The central city of Homs and in particular the opposition district known as Baba Amr has become a critical ground for both sides.
The opposition has lionized it as "Syria's Misrata" after the Libyan city where rebels fought off a brutal government siege. Assad's regime wants desperately to erase the embarrassing defiance in Syria's third-largest city after weeks of shelling, including a barrage of mortars that killed up to 200 people earlier this month. At least nine people were killed in shelling Monday, activists said.
Another massive death toll would only bring further international isolation on Assad from Western and Arab leaders.
"The massacre in Syria goes on," said U.S. Sen. John McCain during a visit to Cairo, where he urged Washington and its allies to find way to help arm and equip Syrian rebels.
McCain, a senior member of the Senate Armed Service Committee, said he did not support direct U.S. weapons supplies to Syrian opposition forces, but has suggested the Arab League or others could help bolster the fighting power of the anti-Assad groups. The U.S., he said, could assist with equipment such as medical supplies or global positioning devices.
"It is time we gave them the wherewithal to fight back and stop the slaughter," he said.
Assad's fall also would be a potentially devastating blow for his close ally Iran, which counts on Syria as its most reliable Arab ally and a pathway for aid to Tehran's patron Hezbollah in Lebanon.
(Watch at left an excerpt of Pelley's interview with McCain)
"The Iranians are already there," McCain told Pelley. "They're already there. All reports confirm that. They're already supplying arms and equipment to Bashar Assad, as are the Russians supplying arms, so right now it's an asymmetric situation with Bashar Assad receiving equipment and actual physical help from Iran, Russia - and the Syrian rebels not receiving equal assistance, certainly not very much."
During his visit to Cairo, McCain urged for "like-minded" Western and Arab nations also to guard against attempts by al Qaeda or other extremists to exploit a leadership vacuum if the regime crumbles.
"For us to sit back and do nothing while people are being slaughtered ... is an affront to everything America stands for and believes in," said McCain, suggesting that the Republicans could seek to make Syria a central campaign issue in this year's U.S. presidential election.
Syria-based activist Mustafa Osso told The Associated Press that Assad's military should face strong resistance as residents plan to fight until "the last person." He added that Homs is facing "savage shelling that does not differentiate between military or civilians targets."
The Baba Amr neighborhood on Homs' southwest edge has become the centerpiece of the city's opposition. Hundreds of army defectors are thought to be taking shelter there, clashing with troops in hit-and-run attacks each day.
Amateur videos posted online showed what activists said were shells falling into Baba Amr. Black smoke billowed from residential areas. Phone lines and Internet connections have been cut with the city, making it difficult to get firsthand accounts from Homs residents.
In Geneva, a spokeswoman for the International Committee of the Red Cross said the group has been in talks with Syrian authorities and opposition groups to negotiate a cease-fire in some of the most violence-torn areas.
"We are currently discussing several possibilities with all those concerned, and it includes a cessation of fighting in the most affected areas," the spokeswoman, Carla Haddad, told the AP.
She said the talks weren't aimed at resolving any of the entrenched political differences.
"The idea is to be able to facilitate swift access to people in need," Haddad said.
Clashes between military rebels and Syrian forces are growing more frequent and the defectors have managed to take control of small pieces of territory in the north as well as parts of Homs province, which is Syria's largest stretching from the border with Lebanon in the west to Iraq and Jordan in the east. Increasingly, Syria appears to be careening toward an all-out civil war.