MOSCOW — Russia said it remains opposed to sanctions against Iran, while China expressed hope for a negotiated solution as senior diplomats from six countries converged in Moscow today to map out the next step toward solving the Iranian nuclear standoff.

The United States and Britain say that if Iran does not comply with the U.N. Security Council's April 28 deadline to stop uranium enrichment, they will seek a resolution that would make the demand compulsory.

So far, Iran has refused to give up uranium enrichment, which the United States and some of its allies suspect is meant to produce weapons. Tehran insists its nuclear program is for peaceful purposes.

Iranian President Mahmoud Ahmadinejad remained defiant today, warning that Iran will "cut the hand of any aggressor" that threatens it.

BAGHDAD, Iraq — A bomb exploded today at a Baghdad cafe frequented by policemen, killing at least seven people and wounding more than 20, police said. In the southern city of Basra, a policeman was gunned down in a drive-by shooting.Three policemen were among those killed in the cafe blast, and the rest were civilians, said police Capt. Ali al-Obeidi.On Monday, U.S. troops repelled an attack in Ramadi by Sunni Arab insurgents who used suicide car bombs, rocket-propelled grenades and automatic weapons in a coordinated assault on the city's main government building and two U.S. observation posts.

VERACRUZ, Mexico — An overcrowded bus speeding home from a religious festival veered off a highway emergency ramp and crashed through a metal barrier, plunging more than 650 feet into a ravine. Fifty-seven people were killed, including a 13-year-old boy.Just three people survived Monday's plunge from the highway, considered one of the 15 most dangerous in Mexico.Police did not immediately know what caused the crash, but said the driver had been trying to maneuver into a lane designed for vehicles that have brake or other mechanical failure as the bus descended a winding mountain road.