By Ivan Watson reporting from Istanbul, Turkey

The bloody internal struggle over the future of Syria is increasingly taking on a wider, regional dimension that could be seen as a proxy war times two.

At one level, it is a showdown of the old Cold War dimension, pitting the United States and other Western countries against Russia and China. But there is a second proxy battle going on, as throughout the Middle East battle-lines are being drawn between governments that support and those that oppose the al-Assad, regime based mostly on allegiance to Shiite and Sunni heritage.

Turkey - Syria's most powerful neighbor - accuses Syrian President Bashar al-Assad of massacring his own citizens. The Turkish prime minister threatened new pressure tactics in an address to Parliament.

"We will start a new initiative at this point with those countries that will be on the side of the Syrian people, and not with the Syrian regime," Turkish Prime Minister Recep Tayyip Erdogan told his Parliament.Moscow is stepping up support for embattled al-Assad, even as Gulf states and Western governments, led by the United States, have either closed their embassies or temporarily recalled their ambassadors from Damascus.

"The Syria matter cannot be sacrificed to rivalries between powers. (The) Syria matter cannot be sacrificed to power balances, polarized struggles similar to the Cold War. Those who struggle for political power via Syria should know that the blood shed there spills on them, too," Erdogan warned on Tuesday.

"This is where the Arab Spring meets the Sunni-Shia struggle meets the Cold War," said Andrew Tabler, a Syria expert at the Washington Institute of Near East Policy and author of the book "In the Lion's Den."

"The tinder is very dry," Tabler said. "In the short term we're looking at a sharp increase of bloodshed in Syria. I do believe in proxy wars and I think this is one of them."

"The increasing divide we're seeing in the Middle East is a sectarian one," said Karim Sadjapour, an analyst at the Carnegie Endowment for International Peace.

Turkey is in the anti-al-Assad camp, along with other majority Sunni Muslim countries like Saudi Arabia, Qatar and other wealthy Gulf Arab states.

Assad's allies include the Shia-led government in Iraq, the Lebanese Shiite movement Hezbollah, and of course Iran.

"The collapse of the Syrian regime would be a huge blow to the Iranian regime because Syria has been its only consistent ally since the 1979 revolution, and Syria allows Iran to continue to offer support to Hezbollah," Sadjapour said. "Whereas Iraq and Lebanon are predominantly Shiite Arabs, in Syria you have a Sunni majority which is not going to be sympathetic to Iran, so the demographics of the situation in Syria are not in Iran's interest. And whatever likely succeeds the Assad regime in Syria is not going to be well oriented towards Tehran."

While Iran is believed to be giving Damascus financial and military support, Turkey has been hosting Syrian opposition groups and activists, like former Syrian Ambassador Bassem Imadi.

"The situation in Syria has to be solved and quickly. If not, the whole problem will spill over to Iraq, Lebanon, Jordan and perhaps Turkey," said Imadi, who is a member of the opposition Syrian National Council's international relations committee.

But while countries like Saudi Arabia, Qatar and Turkey agree that Assad must go, "on (a) more micro level, in terms of how specifically to do that and whether to arm the Syrian opposition, I don't think there's a consensus," Sadjadpour said.

In the midst of this growing geopolitical struggle, Damascus appears to have lost the support of one key Middle Eastern player - the Palestinian movement Hamas. Its leader Khaled Mashal recently abandoned his long-time home in Damascus - a signal, many analysts say, of the Syrian government's growing domestic and international isolation.