U.S. President Barack Obama has signed legislation imposing new sanctions against North Korea in response to Pyongyang's nuclear and missile tests.

The bill calls for imposing mandatory sanctions on anyone assisting Pyongyang over its nuclear and missile programs, cyberattacks and human rights abuses.

The expanded sanctions are designed to deny North Korea the money it needs to develop miniaturized nuclear warheads and the long-range missiles needed to deliver them.

The measure also authorizes $50 million over five years to transmit radio broadcasts into North Korea and support humanitarian assistance programs.

Meanwhile, in another move that will likely stoke the tension with Pyongyang, South Korean Defense Minister Han Min-koo said Thursday that about 15,000 U.S. troops will take part in the annual Key Resolve and Foal Eagle exercises when they begin next month, which is twice the number from last year.

The increased numbers will make it the largest combined military drill ever. North Korea has repeatedly claimed that the drills are in preparation for a northward invasion.

Also Thursday, South Korean intelligence officials informed lawmakers that North Korean leader Kim Jong-un has ordered preparations for terror attacks on South Koreans.

The National Intelligence Service believes the attacks could target anti-North Korean activists, defectors and South Korean government officials. Subways, shopping malls and power stations are also potential targets.

Source: Voice of America