BAGHDAD, (Reuters) – Several mortars or rockets were fired at Baghdad’s fortified Green Zone government district on Tuesday shortly after U.S. Vice President Joe Biden flew in to keep pressure on Iraq’s leaders to make political compromises.

Iraqi police said two suspected mortar rounds landed near the sprawling U.S. embassy compound in the Green Zone, but did not hit it. Biden had met with the U.S. ambassador, Chris Hill, and the top U.S. military commander, General Ray Odierno, just before the mortar strikes. His precise location was being kept under wraps for security reasons, but a Reuters reporter heard a blast during a briefing for journalists by Hill and Odierno. A loudspeaker at the embassy broadcast a warning to duck and take cover.

It was Biden’s second trip to Iraq in three months, and the visit signalled that the Obama administration is anxious to resolve long-standing disputes between Kurdish, Shi’ite and Sunni Arab communities over land and oil that U.S. officials fear could yet rip apart the country.

Violence has dropped sharply in Iraq since the height of a wave of sectarian killings in 2006, due in part to a so-called “surge” of tens of thousands of U.S. troops, but the security gains have not been matched by much political progress.

The security gains themselves remain fragile, as evidenced by Tuesday’s rocket and mortar attacks and two giant truck bombs on Aug. 19 that killed 95 people at the Iraqi foreign and finance ministries and shattered public confidence in Iraq’s police and military.

Since 2006, Washington has pressed Iraq’s Kurdish, and Shi’ite and Sunni Arab leaders, with little success, to put aside differences and compromise on issues such as a new oil law to manage the world’s third-largest oil reserves. But now with U.S combat operations due to end in Iraq by August 2010, the United States is running out of time and influence among Iraq’s leaders to achieve its goal — to leave behind a relatively stable Iraq that can resist efforts by neighbouring Shi’ite Iran to meddle in its affairs. There is no longer any appetite in Washington for the Iraq war. The Obama administration is preoccupied with the deteriorating security situation in Afghanistan and rallying fading support among Americans and sceptical Democrats who control the U.S. Congress for the eight-year-old war there.