SEOUL/WASHINGTON (Reuters) - North Korea ramped up threatening language against the United States on Friday, days before the start of annual joint U.S.-South Korean military exercises, while a bill to stiffen sanctions against Pyongyang advanced in the U.S. Congress.
North Korea regularly protests the drills, which it calls a rehearsal for war and recently stepped up its own air, sea and ground military exercises, adding to tension between the rival Koreas.
"The DPRK will wage a merciless sacred war against the U.S. now that the latter has chosen confrontation," the country's official KCNA news agency said, quoting from an article in the ruling Workers' Party newspaper, the Rodong Sinmum.
The Democratic People's Republic of Korea is also referred to as DPRK.
"Nuclear weapons are not a monopoly of the U.S.," the article said. "The U.S. is seriously mistaken if it thinks its mainland is safe."
In Washington, a bill that would broaden sanctions against North Korea to pressure it into abandoning its nuclear weapons was approved by the House Foreign Affairs Committee.
The bipartisan legislation would impose harsher punishments on foreign companies doing business with Pyongyang and could affect mostly on Chinese companies.
The bill is a response to what lawmakers see as an international failure to rein in North Korea's nuclear weapons program and a cyber attack on Sony Pictures, the entertainment arm of Sony Corp, that has been blamed on Pyongyang.
U.S. Undersecretary of State for Political Affairs Wendy Sherman told an audience at Washington's Carnegie Endowment think tank that international pressure on North Korea was growing. She said Pyongyang was increasingly isolated and trying "to conceal a weak hand ... through a clenched fist".
Sherman said Washington was open to talks with Pyongyang, but they must be centered on the nuclear issue. "There are other things that can be discussed ... but at the core is the nuclear program," she said.
North Korea frequently makes threats against the United States and South Korea, which said on Tuesday the allies would begin eight weeks of joint exercises on March 2.
On Friday, North Korea said the United States was "much upset by the fact that there may be a sign of detente on the Korean peninsula, thanks to the DPRK's initiative and efforts to achieve peace this year".
However, overtures for dialogue by both Koreas in recent months have stalled, with Pyongyang recently describing inter-Korean relations as "inching close to a catastrophe."