BAGHDAD, Aug. 5 (Xinhuanet) -- US forces have launched a new offensive against insurgents in the restive Anbar province in western Iraq but their enemies are equipped with enhanced tactics and weapons.

    The operation, dubbed Quick Strike, was launched on Wednesday in the Euphrates River valley, hours after 14 US marines were killed in Haditha, a town on the Euphrates River, in the deadliest roadside bomb attack on the US troops since the war began in March 2003, US military said on Friday.

    It said the assault focused on several violent towns of Anbar province including Haditha, Haqlaniyah and Parwana, some 250 km northwest of Baghdad.

    About 1,000 US and Iraqi troops, including Special Operations forces, swept Haqlaniyah, and even an airstrike was carried out on insurgent positions outside the town, according to the statement.

    However, the American troops suffered heavy losses from their tougher enemies.

    In the past ten days, at least 46 US soldiers were killed, most of them in Anbar. Over 1,820 US soldiers have died in Iraq since the US-led invasion in March 2003. No sign indicates that insurgent attacks are fading away.

    Some analysts said insurgents have adopted the tactics of decentralized command and fast movement which is hard to locate. They also avoid direct confrontation with US military.

    "They started to use this guerrilla-like method after the big battle in Fallujah in November 2004, where they are cornered in small area and became easy targets," analysts said.

    New York Times reported on Thursday that recent attacks showed roadside bombs has become more fatal with greater power and improved accuracy, posing a serious challenge to US forces. Enditem