India and South Africa join the UN Security Council on Saturday, bolstering a bloc of countries on the powerful panel that may be reluctant to support new sanctions against Iran over its nuclear program.
However, barring any shocking revelations about Tehran's nuclear program, some analysts suggest that Washington might forgo pursuing new UN steps against Iran in 2011. That may be good news for oil markets, since Western diplomats say Iran's energy sector would be the next logical area to sanction.
Germany, Portugal and Colombia join the 15-nation Security Council on January 1, also for two-year stints as rotating members.
Apart from Iran's nuclear ambitions, council diplomats point to other key issues on the council agenda in 2011 -- the threat of new civil wars in Ivory Coast and Sudan, tensions on the Korean peninsula, Security Council expansion and the expected re-election of Secretary-General Ban Ki-moon for another five-year term starting in 2012.
The five newcomers to the Security Council are not expected to impact its approach to North Korea, where the veto-wielding permanent member China plays a decisive role, or Ivory Coast, where the entire council voiced support for the UN-certified results of last month's presidential election.
Newcomer South Africa has vowed to raise the possibility of suspending a genocide indictment against Sudanese president Omar Hassan al-Bashir if a January 9 referendum on south Sudan's independence goes ahead peacefully. Southerners are widely expected to choose secession over remaining under Khartoum.
If the vote goes well, diplomats say the United States, Britain and France might consider suspending the indictment.
But the new composition of the council could complicate matters for US president Barack Obama's administration should it choose to pursue a fifth round of UN sanctions against Tehran for refusing to freeze its nuclear enrichment program.
Four rounds of increasingly restrictive UN sanctions on Iran have targeted its nuclear, missile, financial and shipping industries. These have been supplemented by even more draconian U.S. and European Union steps that included energy sanctions.
Tehran insists its atomic program is peaceful and not intended for producing weapons, as Western powers suspect.
The addition of the five rotating members is not the only change for the council. An increasingly self-confident China has been using its diplomatic weight to protect countries that Beijing considers to be its allies.
Beijing fought hard to remove all but one Iranian bank from a list of firms in the fourth round of UN sanctions in June.
It later blocked US attempts to have the council rebuke Myanmar's military rulers and North Korea over its nuclear program.
When South Africa was last on the council in 2007-2008, it voted twice in favor of sanctioning Iran but joined China and Russia in lobbying to dilute the proposed punitive measures.
Brazil, on the council through the end of 2011, has also been reluctant to punish Iran. It joined Turkey in June to cast the first ever votes against Iran sanctions on the Security Council. Previously there had only been one abstention.
India, which was last on the Security Council in 1991-1992, has close commercial ties to Iran, and has also indicated that sanctions were not the right strategy.
But George Perkovich of the Carnegie Endowment for International Peace said that the latest developments in India-Iran relations suggested India's support could be won.
Tehran has threatened to block oil sales to India after it implemented prohibitive new rules on trade with Iran that earned New Delhi praise from Washington.
Joseph Cirincione, president of the Ploughshares Fund, a global security foundation, said that if there are any new revelations about hidden nuclear sites in Iran in 2011, or similar developments, the Indians and South Africans would probably be amenable to new punitive steps against Tehran.
"If Iran does something outrageous, it's going to be hard for countries like India and South Africa to resist further sanctions," Cirincione said.
Obama's open door to engagement with Iran will help to ensure that India, South Africa, China and Russia keep "an open mind" regarding further UN sanctions in 2011, he added.
But absent any "outrageous" moves by Iran, Cirincione and Mark Fitzpatrick of the International Institute for Strategic Studies in London said that Washington and its EU allies would probably forgo a push for new UN sanctions in 2011.
"In the meantime, the US will tighten the financial and other unofficial sanctions that have proven to be the most burdensome for Tehran," Fitzpatrick said.