TOKYO (AP) — North Korea says it will make the United States pay a heavy price if a proposal Washington is backing to impose the toughest sanctions ever on Pyongyang is approved by the U.N. Security Council this week.

The North's Foreign Ministry issued a statement Monday saying it is watching the United States' moves closely and threatened it is "ready and willing" to respond with measures of its own.

The United States has called for a vote Monday on new U.N. sanctions against North Korea.

Last Tuesday, the U.S. circulated a draft resolution proposing the toughest-ever U.N. sanctions on North Korea, including a ban on all oil and natural gas exports to the country and a freeze on all foreign financial assets of the government and its leader, Kim Jong Un.