Worried by Iran's deepening involvement in the Arab world, Saudi Arabia has been working quietly to curtail the Persian nation's influence and prevent the marginalization of Sunni Muslims in the region's hotspots.
In every major conflict zone in the region - in Iraq, Lebanon and the Palestinian Authority - the Sunni kingdom has been putting its economic and diplomatic weight behind allies in direct confrontation with groups backed by Shiite Iran.
Analysts say the tug-of-war between the two Mideast powers signals a new chapter in an uneasy relationship, one that has swung over the years between wariness and - at certain times - outright coldness and confrontation. On the surface, both countries have maintained the same civil front that has marked ties since a thaw in relations in the early 1990s.
"But events on the ground indicate that the two countries are working against each other as their differences are played out outside their borders," said Ibrahim Bayram, a Beirut-based journalist for An-Nahar newspaper who follows Lebanon's pro-Iranian Hizbullah group.
The vicious violence pitting Sunnis against Shiites in Iraq, the quick rise of Iran's influence in that country, Teheran's support for Hamas and the events in Lebanon - where Hizbullah is staging open protests to bring down the Saudi-backed government of Fuad Saniora - have cast a shadow on Saudi-Iranian ties.
In addition, the kingdom has expressed concern over Iran's nuclear program. The United States contends that Iran seeks to develop nuclear weapons, which Iran denies. But Saudi Arabia is worried about even a peaceful program because of the possible environmental threat - and fears of the Gulf getting caught in the middle of any fight between Iran and US troops stationed in Kuwait, Qatar and Bahrain.
A Saudi official says Iran has sent messages expressing its desire to work with the kingdom to resolve the area's conflicts.
"But the deeds on the ground are louder than those messages," a Saudi official said.
"That's making us more cautious" in dealing with Iran, he added on condition of anonymity because of the sensitivity of the issue.
It has also made the kingdom more determined to be involved in exploring ways to find a settlement for the upheavals.
It has stepped up attempts to reconcile Iraq's fractious groups and has invited several Iraqi leaders for talks, including anti-American Shiite cleric Muqtada al-Sadr and Harith al-Dhari, head of Iraq's influential Sunni Association of Muslim Scholars. It has also been talking to Iraq's Sunnis to urge them to renounce violence and increase their involvement in the political process.
The kingdom has not backed down from its support for Lebanon's Saniora and the beleaguered Palestinian President Mahmoud Abbas.
The relationship between Iran and Saudi Arabia has long been uneasy, especially after the fiery spiritual leader Ayatollah Ruhollah Khomeini deposed Iran's shah in 1979 and established an Islamic republic. The Islamic revolution alarmed the Saudi leadership, which feared it would be next to fall.
Saudi Arabia sided with Baghdad in the 1980-88 Iran-Iraq war, and Riyadh and Teheran were openly hostile to each other at the height of the conflict.
Iran frequently called on Muslims to overthrow the Saudi ruling family, seize its oil wealth and strip it of its role as guardian of Islamic holy places. The kingdom accused Teheran of trying to undermine its security, and Saudi officials denounced the Iranian regime as a "group of terrorists."
The kingdom broke off relations with Iran in 1988, a few months after Iranian pilgrims rioted in the Saudi holy Muslim city of Mecca. But distrust between the two countries eased after Khomeini's death in 1989, and diplomatic relations were restored shortly after the 1991 Gulf War.
Saudi King Abdullah worked hard to mend ties even before he became monarch last year.
Saudi analysts say Iran is now trying to wrest the traditional leadership role that Saudi Arabia has played in the region by involving itself in the turmoil engulfing the Arab world.
But Saudi Arabia will "not allow Iran to expand at its expense as a big regional power," said Dawood al-Shirian, a Saudi journalist.
"Iran is acting as a Persian state and not as an Islamic state," he said. "The conflict in the region is not a Sunni-Shiite conflict. It's a Persian-Arab conflict."
The view from Iran is different, said Mashaallah Shamsolvaezin, an adviser to the Middle East Strategic Studies Center in Teheran, an organization closely affiliated with the Iranian Foreign Ministry.
Shamsolvaezin said a change in Iranian foreign policy - one in which Teheran has decided to focus on improving economic and political ties with Middle Eastern countries instead of Europe - has prompted Saudi fears.
"Is this political shift coming at the expense of Middle Eastern countries like Saudi Arabia and Egypt? No," said Shamsolvaezin.
He argued the Saudi and Iranian policies in Iraq and Lebanon are not necessarily opposed, but could be viewed as "complimentary."
Shamsolvaezin also said Iran "does not discriminate against sects" and that its support for the Palestinian militant Hamas, a Sunni Muslim, Arab group, is an example of that.
He blamed Iranian President Mahmoud Ahmadinejad's "radical" rhetoric for Teheran's failure to send a reassuring message about its policy shifts.
"His statements not only have not helped. They have hurt Iran's strategic policies," he said.