SEOUL (BLOOMBERG) - North Korea hasn't fired a missile for 60 days, but that may have more to do with its own winter training cycle than with Pyongyang easing off on provocations.

Since Kim Jong Un took power in late 2011, only five of the isolated nation's 85 rocket launches have taken place in the October-December quarter, according to The James Martin Centre for Nonproliferation Studies' North Korea Missile Test Database.

The Korean People's Army regularly enters its training cycle every winter "and getting ready for it involves a calm before the storm," said Van Jackson, a strategy fellow at the Center for Strategic Studies at Victoria University of Wellington.

"Fall is the harvest season, and a lot of military labour is dedicated to agricultural output when not in war mode; inefficient, but it's the nature of the North Korean system," said Jackson, a former US Department of Defence adviser.

"It's a routine, recurring pattern, which means we should expect a surge in provocations in the early months next year."

North Korea's last launch was on Sept 15, when the isolated state fired its second missile over Japan in as many months - a rocket that flew far enough to put the US territory of Guam in range.

Joseph Yun, the US' top North Korean official, was reported by the Washington Post as saying on Oct 30 that if the regime halted nuclear and missile testing for about 60 days, it would be the signal Washington needs to resume direct dialogue with Pyongyang.

Secretary of State Rex Tillerson on Friday (Nov 10) denied the US had any such window.

South Korea's military said Monday (Nov 13) it's keeping its troops on full combat readiness against North Korea's possible provocations as North Korean soldiers are preparing for their months-long winter training, according to Yonhap News.