Attacks across Iraq kill 55

? Bombers and gunmen killed 55 Iraqis in two dozen attacks spanning the country Wednesday, mostly targeting security forces in seemingly coordinated strikes the day after the number of U.S. troops fell below 50,000 for the first time since the start of the war.

Insurgents have been stepping up their attacks on Iraq’s security forces in recent months as the U.S. has trimmed its military presence in the country. At least half of those killed — 31 — were Iraqi soldiers and policemen.

There were no claims of responsibility for the spate of attacks. But their scale and reach, from one end of the country to the other, underscored insurgent efforts to prove their might against security forces and political leaders who are charged with the day-to-day running and stability of Iraq.