The United States says cooperation between Syria and Iraq to secure their common border is badly needed and long overdue.

State Department spokesman Richard Boucher commented on Iraqi border issues Monday amid reports of Syrian pledges to help promote Iraq's stability and security.

Mr. Boucher said Iraq's neighbors are duty-bound to monitor and regulate their borders with Iraq. "We think that neighboring countries have a particular responsibility to stem the inflow of foreign fighters, terrorists and weapons, and to combat smuggling. We think there is more that needs to be done," he said. "We welcome any steps by the Syrian government or the Syrian government in cooperation with Iraq to better control the flow over its border."

Sunday, Iraqi Deputy Prime Minister Barham Saleh announced an agreement with Syria to set up a joint patrol along the two countries' 600-kilometer common border. Mr. Saleh, who spoke in Damascus after meeting with Syrian President Bashar al-Assad, said the initiative would focus on preventing the infiltration of terrorists and militants into Iraq.

State Department spokesman Boucher described a joint Iraqi-Syrian border patrol as a "welcome development."

Iraqi and coalition officials have long maintained that many perpetrators of violence in Iraq originated outside the country, perhaps most notably Jordanian terrorist Abu Musab al-Zarqawi.