Barack Hussein Obama wasted no time plunging into foreign policy on his first full day in office yesterday, finally freed from the constraints of tradition that had forced him and his staff to remain silent about world affairs until he became president.

Obama made a flurry of calls to Arab and Israeli leaders in a signal that Middle East peacemaking is a top priority following Israeli aggression against Gaza.

A Palestinian spokesman said that Obama had told Palestinian President Mahmoud Abbas that he was the recipient of his first call as the 44th US president.

The White House source confirmed the calls, on condition of anonymity, and said Obama also telephoned Israeli Prime Minister Ehud Olmert, Egyptian President Hosni Mubarak and Jordan’s King Abdallah.

On Tuesday, as Obama took his oath of office, his senior staff made their first moves. Within hours of his inauguration, Obama requested a halt to military trials at the Guantanamo detention camp. He also ordered last-minute regulations signed by his predecessor, George W. Bush, to be put on hold.

And Obama promised that on his first day in office he would give his military commanders a new mission — to end the war in Iraq.

As his first day as president, Obama began the day with a prayer service at Washington’s National Cathedral — a tradition dating to the time of George Washington, the first US president.

Obama then met with economic and military advisers, where they discussed an $825 billion economic rescue package — as well as the Iraq and Afghanistan wars. Congressional leaders say they intend to pass the economy stimulus bill by the middle of February.

Obama has promised to withdraw combat troops from Iraq within 16 months — and the Iraqi government has said that US forces are welcome to leave before the 2012 deadline set at the end of last year.

More than 140,000 US troops are still stationed in Iraq, five years after an invasion, which the new president consistently opposed.

Aides also announced that the nation’s new president plans to name former Sen. George Mitchell, who is half-Lebanese, as his Middle East envoy, sending a signal that the new administration intends to move quickly to engage warring Israelis and Palestinians in efforts to secure the peace.

Mitchell’s appointment will follow expected Senate vote to confirm Hillary Clinton as secretary of state. The Obama administration’s request for a 120-day suspension of legal proceedings for detainees at Guantanamo is a clear break with the approach of the outgoing Bush administration. The US military prison at Guantanamo Bay became a symbol of excess in the war on terror waged by his predecessor George Bush.

Obama made international news during his inaugural address Tuesday when he told the world’s Muslims that his administration will be looking for a “new way forward, based on mutual interest and mutual respect.”

Obama underscored that his foreign policy approach toward Muslim nations will be firm on leaders “who seek to sow conflict or blame their society’s ills on the West” but that “we will extend a hand if you are willing to unclench your fist.”

Past generations understood that more than “missiles and tanks” were required to face down global threats, Obama said; so were “sturdy alliances and enduring convictions.” “They understood that our power alone cannot protect us, nor does it entitle us to do as we please,” he said.

“Guided by these principles once more, we can meet those new threats that demand even greater effort —- even greater cooperation and understanding between nations.”

In particular, he said, that will include forging peace in Afghanistan, leaving Iraq “responsibly,” and working against the threats of nuclear power and global warming.

Meanwhile, he said, “we can no longer afford indifference to suffering outside our borders.”