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Syria crisis: Russia warns Obama against 'violation' of international law

Activists release amateur video reportedly showing the shelling of Aleppo by Syrian government forces while Japan confirms a war correspondent, Maya Yamamoto, was killed by gunfire in Syria. NBCNews.com's Dara Brown reports.

Updated at 12:00 p.m. ET: Russia rebuffed President Barack Obama's threat of unilateral action against Syria Tuesday, as officials said 2,500 refugees fled across the border into Turkey in just 24 hours – one of the highest daily refugee flows of recent weeks.

Russian Foreign Minister Sergei Lavrov, speaking after meeting China's top diplomat, said Moscow and Beijing were committed to "the need to strictly adhere to the norms of international law ... and not to allow their violation".

Obama draws 'red line' for Syria on chemical and biological weapons

Obama on Monday threatened "enormous consequences" if his Syrian counterpart used chemical or biological arms or even moved them in a menacing way.

The president used some of his strongest language yet to warn Assad not to use chemical or biological weapons – after Syria acknowledged for the first time that it had such weapons and could use them if foreign countries attacked it.

At an impromptu White House news conference, President Obama comments on GOP Mo., Senate candidate Todd Akin's remarks about rape, Mitt Romney's refusal to release more than two years' worth of tax returns, and the unrest in Syria. Watch the entire news conference.

"We have been very clear to the Assad regime, but also to other players on the ground, that a red line for us is (if) we start seeing a whole bunch of chemical weapons moving around or being utilized," he said. "That would change my calculus."

Syria 'ready to discuss' Assad's resignation, deputy PM says

"We cannot have a situation where chemical or biological weapons are falling into the hands of the wrong people," Obama said, perhaps referring to Lebanon's Shiite Hezbollah group, an Iranian-backed ally of Assad, or to Islamist militants.

Turkey's foreign minister has warned it can accommodate no more than 100,000 refugees and that the United Nations may need to create a "safe zone" within Syria to shelter any beyond that number.

Goran Tomasevic / Reuters

After months of protests and violent crackdowns, a look back at the violence that has overtaken the country.

Thousands of refugees
A Turkish official told Reuters on Tuesday that about 2,500 people fleeing violence in Syria had entered Turkey in the preceding 24 hours, most of them entering the southeastern Turkish province of Hatay.

Turkish journalist Mahir Zeynalov reported on Twitter that four Syrian colonels and two captains crossed the border early Wednesday.

PhotoBlog: Clashes over Syrian conflict in Lebanon leave ten dead

Turkey is now sheltering close to 70,000 Syrian refugees and is struggling to accommodate the influx, which rose after a bomb attack near the border killed eight, spreading panic.

In Lebanon, street battles between Sunnis and Alawites continued for a second night running, fueled by conflicting loyalties in the conflict across the border. The BBC reported that seven were killed and more than 70 wounded in the country's second-largest city, Tripoli.

Syrian President Bashar Assad, an Alawite, is battling largely Sunni opposition fighters. Lebanese Prime Minister Najib Mikati, himself a Sunni, appealed to both sides to end the "absurd battle" in Tripoli.

In Syria itself, the army deployed tanks on a ring road surrounding Damascus on Wednesday and shelled southern neighborhoods where rebels operate, in the heaviest bombardment on the capital since the army reasserted control last month, residents said.

At least eight people were killed in the shelling, which was accompanied by an aerial bombardment, on the Kfar Souseh, Daraya, Qadam and Nahr Aisheh neighborhoods, they told Reuters.

Regional news channel Al-Jazeera reported that at least 24 people were killed across the country on Tuesday, among them women and children in Aleppo - the city over which the rebel Free Syrian Army (FSA) claims two-thirds control, and where a Japanese journalist was killed on Monday.

Activists: Japanese journalist killed in Aleppo

"We now control more than 60 per cent of the city of Aleppo, and each day we take control of new districts," said Abdel Jabbar al-Okaidi, a colonel with the FSA. He went on to list some 30 districts which he claimed were under FSA control, including about half of the embattled neighborhood of Salaheddin.

But a security source in Damascus rejected the claims, according to the AFP news agency, calling them "completely false".

Syrian President Bashar Assad makes a rare public appearance for the Muslim holiday of Eid on Sunday. NBC's Ayman Mohyeldin reports.

Likened to Iraq invasion
Syrian soldiers killed a journalist sympathetic to the rebels during a raid in Damascus on Wednesday. Mosaab al-Odaallah, who worked for the state-run Tishreen newspaper, was shot at point-blank range at his home by troops conducting house-to-house raids in the southern Nahr Eisha district of the capital, opposition activists said.

Massoud Akko, head of the public freedoms committee at the underground Syrian Journalists Association, said Odaallah's death brought to 54 the number of Syrian journalists, bloggers and writers killed by security forces during the uprising.

"Most have been killed with shots to the head. The regime appears to have adopted a systematic policy of killing journalists and social media activists," Akko told Reuters by telephone from Berlin.

Earlier, Syria's deputy Prime Minister Qadri Jamil said Obama's talk of action against Syria was media fodder.

Speaking after the news conference held by Russia's Lavrov, Jamil said the West was seeking an excuse to intervene, likening the focus on Syria's chemical weapons with the run-up to the 2003 invasion of Iraq by U.S.-led forces and the focus on what proved to be groundless suspicions that Saddam Hussein was concealing weapons of mass destruction.

"Direct military intervention in Syria is impossible because whoever thinks about it ... is heading towards a confrontation wider than Syria's borders," he told a news conference in Damascus.

Meanwhile, the Los Angeles Times reported the concerns of Christians, who make up about 10 per cent of Syria's population. It said Christians fleeing the fighting have detected an increasingly radicalized Islamist strain among the rebels that makes them fear for their future.

Reuters contributed to this report.

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