Nations race to prevent backsliding on North Korea sanctions

Armed with extraordinary new U.N. sanctions, nations are racing to ensure that North Korea's biggest trading partners actually carry them out, an elusive task that has undercut past attempts to strong-arm Pyongyang into abandoning its nuclear weapons.

President Donald Trump is demanding full and speedy implementation of the new penalties. But his top diplomat is also laying out a narrow path for the North to return to negotiations.

Secretary of State Rex Tillerson says if the North stops testing missiles for an "extended period,'' the U.S. might deem North Korea ready to talk. But he says it won't be a matter of a mere 30-day pause leading to the U.S. being willing to talk.

Tillerson says, "We'll know it when we see it.''