Damascus and Washington have taken steps recently toward easing their strained relations. Syrian Foreign Minister Walid Moallem met briefly with Secretary of State Condoleezza Rice last month.
The Syrian Foreign Ministry summoned the top U.S. and Iraqi diplomats in Damascus yesterday and complained of "dangerous aggression," the news agency said. It demanded that Iraq launch an immediate investigation into the attack and that it prevent foreign forces from using Iraqi territory to launch attacks.
It was unclear how the raid would affect U.S.-Iraqi negotiations over an agreement to extend the American military presence in Iraq. Syria and Iran have opposed the agreement, in part out of fear that U.S. forces would use Iraq as a base to strike at them.
U.S. officials have asked Arab leaders in the past to pressure Syria to tighten its visa restrictions on military-age males in an effort to prevent would-be militants from flying to Damascus then making their way to the Iraqi border. Military units inside Iraq have focused on shutting down the "rat lines" that shuttle militants from the Syrian border to Ramadi and then to Baghdad.
This month, Gen. David Petraeus, the former top commander in Iraq, said those efforts had helped cut the number of foreign fighters crossing the Syrian border from about 100 a month to 20. But he made clear that more needs to be done.
In recent weeks, U.S. commanders have increased their focus on the threat from militants within Syria and blamed for cross-border attacks in western Iraq and for fueling violence in Mosul.
"The Iraqi security forces and the Iraqi intelligence forces feel that al-Qaida operatives and others operate, live, pretty openly on the Syrian side," Marine Maj. Gen. John Kelly, commander of U.S. troops in western Iraq, said at a briefing for reporters last week. "And periodically, we know that they try to come across."
Kelly said that after the May attack Iraqi security forces have tried harder to secure the border.
