WASHINGTON — The United States said today it is “very hard to imagine” that it can go ahead with its offer of food aid if North Korea proceeds with its planned rocket launch.

State Department spokesman Victoria Nuland said U.S. now had “grave concerns” about the Feb. 29 agreement under which North Korea agreed with the U.S. on nuclear concessions and a moratorium on missile tests in return for 240,000 tons of food aid.

In a surprise announcement today, North Korea said it plans in April to launch a satellite into space on the back of a long-range rocket.

The U.S., South Korea and other critics say the rocket technology overlaps with belligerent uses and they condemn the satellite program as a disguised way of testing military missiles in defiance of a U.N. ban.

Nuland told a news briefing that a rocket launch would call into question Pyongyang’s good faith and would not create an appropriate environment to go ahead with the food shipments.