Syrian tanks and troops have massed 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 ceasefire to allow emergency aid in.
A flood of military reinforcements has been a prelude to previous offensives by President Bashar al-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 lionised 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 US senator 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 US 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 US, 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. But 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 US presidential election.
But US Secretary of State Hillary Clinton, on a visit to Mexico on Monday, dodged a question about whether the US could accept Arab countries or others arming the Syrian rebels.
"We are all working for the planned friends of Syria meeting at the end of this week, which we think will give us a chance to come together and chart a way forward," she said.
She said the meeting in Tunisia "will demonstrate the Assad regime is increasingly isolated and that the brave Syrian people need our support and solidarity".
But she said that should be expressed through humanitarian help and encouragement to the Syrian opposition to promise that everyone they will be represented in a new Syria.
In Cairo, Arab League Secretary-General Nabil Elaraby suggested at a news conference that Russia and China - two countries that recently supported Damascus by vetoing a UN Security Council resolution condemning Assad's regime - may be shifting their positions.
"There are some indications, especially from China and to some degree from Russia that there may be a change in their stance," he said, without elaborating.
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 civilian targets".
The Baba Amr neighbourhood on Homs' southwest edge has become the centrepiece 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 ceasefire in some of the most violence-torn areas.
The UN last gave a death toll for the conflict in January, saying 5,400 had been killed in 2011 alone. But hundreds more have been killed since, according to activist groups. The group Local Coordination Committees says more than 7,300 have been killed since March of last year. There is no way to independently verify the numbers, however, as Syria bans almost all foreign journalists and human rights organisations.
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