Supporters of Syrian President Bashar al-Assad rally on April 1 in Istanbul, Turkey, as delegates from dozens of countries gather to push for ways to end the deadly violence in Syria. Since the crisis began in March 2011, the United Nations estimates more than 10,000 people have been killed. 
Syrian youths wave national flags while army troops drive out of Daraa on May 5, 2011. During a weeklong military lockdown of the town, dozens of people were reportedly killed in what activists described as an "indiscriminate" shelling of the town. 
U.S. Secretary of State Hillary Clinton speaks to the press in Washington on August 18, 2011. Clinton said U.S. sanctions on Syrian oil "strike at the heart of the Syrian regime." 
Arab foreign ministers attend an emergency meeting at the Arab League headquarters in Cairo on October 16, 2011, to discuss the crisis in Syria. 
A Syrian man who was wounded in a suicide attack rests at a hospital in Damascus on December 23, 2011. Suicide bombers hit two security service bases in the Syrian capital, killing dozens of people. 
A day after the twin suicide bombings, Syrian mourners pray over the coffins of the 44 people killed during a mass funeral in Damascus. 
Syrian refugees walk across a field before crossing into Turkey on March 14. International mediator Kofi Annan called for an immediate halt to the killing of civilians in Syria as he arrived in Turkey for talks on the crisis. 
A Free Syrian Army rebel mounts his steed in the Al-Shatouria village near the Turkish border in northwestern Syria on March 16, a year after the uprising began. The Free Syrian Army is an armed opposition group made up largely of military defectors. 
Syrian rebel fighters man a checkpoint leading into the town of Taftanaz in the rebel stronghold province of Idlib on March 20. 
Thousands of Syrians wave their national flag and hold portraits of President Bashar al-Assad and Lebanon's Hezbollah chief Hassan Nasrallah, right, during a rally to show support for their leader on March 29 in Damascus. 
A U.N. observer speaks with Syrian rebels and civilians in the village of Azzara on May 4, days before the country's parlianemtary polls were held against a backdrop of unrest. 
Members of the Free Syrian Army return to Qusayr on May 12 after an attack on Syrian regime forces in the village of Nizareer, near the Lebanese border in Homs. 
People gather at a mass burial on May 26 for victims reportedly killed during an artillery barrage from Syrian forces in Houla. The attack left at least 108 people dead, including nearly 50 children, according to the United Nations. 
Syria's President Bashar al-Assad waves as he arrives for a speech to Syria's parliament in Damascus on June 3. The embattled president denied that government forces were behind the "outrageous" massacre in Houla. 
A Syrian woman sits with her grandson outside a damaged building after attacks in the Syrian village of Treimsa on July 13. More than 200 people were massacred in the town, according to activists. 
The death toll in Syria on July 12 reached 287, making it the bloodiest day in Syria since the uprising began. As it has done consistently, Syrian state television blamed "armed terrorist groups" for the killings. 
A Syrian demonstrator holds an opposition flag during a protest in Damascus on July 2. There have been increasing reports of violence in the Syrian capital. 
- NEW: Intense shelling hits several areas in Damascus, an opposition group says
- U.N.-Arab League envoy Kofi Annan is set to meet Russian President Vladimir Putin
- At least 97 people were killed across Syria on Monday, an opposition group says
- Russia's foreign minister slams Western countries trying to change Russia's position
Are you in Tremseh in Hama province? Send photos and stories to CNN iReport.
(CNN) -- For the third straight day, fierce clashes erupted in the Syrian capital Tuesday as fighters braced for a major showdown in the pivotal city, opposition activists said.
"The battle for Damascus is coming," said Abdulhameed Zakaria, a Syrian army colonel who defected and joined the rebel Free Syrian Army.
Several areas of Damascus came under intense shelling early Tuesday, the opposition Local Coordination Committees of Syria said, and explosions rocked the neighborhoods of Tadamon, Midan and Nahr Aisha.
But the violence wasn't limited to the Syrian regime's seat of power.
A Syrian ambassador defects 
Witness to slaughter in Syria 
'Syria has become a schizophrenic place' Warplanes hovered over the southern city of Herak and pummeled it with shelling, the LCC said. The group said at least two rockets fell on the city.
Amid the spiraling chaos, U.N.-Arab league special envoy Kofi Annan is set to meet Russian President Vladimir Putin in Moscow on Tuesday.
Russia and China, which have commercial deals with Syria, have used their veto power at the U.N. Security Council to block some of the toughest draft resolutions against the Syrian regime.
Countries such as the United States have criticized Russia, saying its actions in the Security Council have helped Syrian President Bashar al-Assad's forces to continue a lethal crackdown on dissidents.
On Monday, Russian Foreign Minister Sergey Lavrov slammed Western countries that are trying to change Russia's stance.
"The track record of those who try to make us step aside from this position has a lot of deplorable instances of unilateral military actions, and the results are well remembered by everybody," Lavrov told reporters.
With violence spreading throughout Syria, the International Committee of the Red Cross said the conflict is essentially a civil war.
The declaration officially applies the Geneva Conventions to violence throughout the country. International humanitarian law now applies "wherever hostilities take place," the ICRC said Monday.
The Red Cross generally does not use the term "civil war," but describes the Syrian crisis as a "noninternational armed conflict." In April, the organization declared such a conflict in Homs, Hama and Idlib, but now the conflict exists throughout the country, ICRC spokesman Sean Maguire said.
'Massacres in Syria send terror message' 
Syria's chemical weapons 
U.N. sets deadline for Syria "In theory," he said, the Red Cross announcement could affect prosecutions by the International Criminal Court in the future. However, for the court to look at the situation in Syria, a referral from the U.N. Security Council would be required, Maguire noted.
On the same day Maguire spoke, at least 97 people were killed Monday, the LCC said. The carnage was spread across the country: 30 deaths in Hama, 21 in Homs, 13 in Aleppo, 11 in Damascus, eight in Daraa, seven in Deir Ezzor, four in the Damascus suburbs and three in Idlib, according to the LCC.
CNN cannot confirm details of reported violence because Syria has restricted access to the country by international journalists.
Meanwhile, many nations have expelled Syrian ambassadors, with Morocco becoming the latest to do so Monday. Syria responded by declaring Morocco's ambassador persona non grata.
Since the crisis began in March 2011, the United Nations estimates more than 10,000 people have been killed in the violence; opposition activists say more than 15,000 have died.
Throughout the conflict, al-Assad's government has consistently blamed violence on "armed terrorist groups," and reported on its security forces "martyred" in attacks.
CNN's Josh Levs, Holly Yan, Ivan Watson and Hamdi Alkhshali contributed to this report.
