North Korea refused to sign a non-aggression pact that U.S. Secretary of State John Kerry offered last week on condition of denuclearization, the Associated Press reported.

In a statement carried by the North’s official state media on Saturday, Oct 12, the National Defense Commission spokesman said the U.S. should stop sanctions meant to punish its February nuclear test and provocations including military exercises on the Korean Peninsula.

Earlier this week, North Korea criticized joint two-day naval drills among the U.S., South Korea and Japan as preparations for attacking the North. The allies said these drills were defensive in nature.

During his trip to Japan, Kerry said the door for negotiation with North Korea is open if it abandons nuclear weapons and complies with international demands.

The North’s statement came as the mother of an American held in North Korea visited her son for the first time in his 11-month detention.

Earlier this month, American and Japanese officials announced that the U.S. military will next year begin flying Global Hawk surveillance drones from Japan on missions to monitor North Korea.

According to a report in the Washington Post, the Air Force plans to base two or three of the high-altitude unmanned aerial vehicles made by Falls Church, Va.-based Northrop Grumman Corp. from an as-yet unspecified base in Japan.

U.S. drones, including the Global Hawk, flew over Japan in 2011 to collect data and imagery of the Fukushima Daiichi nuclear power plant, which had a partial meltdown after a tsunami struck the region. But the jet-powered military aircraft has never been stationed in the country before.

The Air Force’s RQ-4 Global Hawk is the biggest unmanned aerial vehicle in the U.S. arsenal.