With satellite images showing North Korea continuing to ready nuclear-test facilities, Pyongyang on Tuesday suggested it feels considerable leeway on timing.
"There is no statute of limitations to the D.P.R.K.'s declaration that it will not rule out a new form of nuclear test clarified by it in the March 30 statement," a North Korean foreign ministry spokesman said in a statement disseminated by regime-controlled media.
The spokesman also rebuked U.S. President Obama for his recent trip to the region, saying it was "dangerous" and risked bringing a "more acute confrontation and nuclear arms race to Asia", Agence France-Presse reported.
During his visit to South Korea, the U.S. leader said the North could be punished with tougher sanctions if conducts a fourth underground nuclear explosion at its Punggye-ri test site.
High-resolution commercial satellite photographs taken on Tuesday show activity at both the "South Portal" area and "West Portal" area of the test site, the Institute for Science and International Security concluded in a new image analysis.
Activities were detected last week around the entrances of two test tunnels in the South Portal area, though it was not clear from the analyzed images whether the work was related to placing nuclear devices in each of the tunnels.
It is also not certain what the detected activities at the West Portal area mean, according to the ISIS analysis.
"Could North Korea be using the West Portal to assemble a nuclear device for detonation in the South Portal, preparing the West Portal for an explosion either individually or in conjunction with one in the South Portal, or carrying out some other type of activity there?" the analysis ponders.
Country expert Bruce Klingner In a Tuesday column for the website 38 North argued that if Pyongyang does detonate another nuclear device, Washington should respond with much tougher financial sanctions than it has in the past.
The Heritage Foundation's Northeast Asia fellow recommended the Obama administration impose third-party sanctions on entities -- particularly those in China -- that do business with blacklisted North Korean firms; define Pyongyang as a primary money laundering concern, perhaps under the Patriot Act; and sanction "the entire North Korean government," instead of solely individuals and agencies, as has been past practice.
This article was published in Global Security Newswire, which is produced independently by National Journal Group under contract with the Nuclear Threat Initiative. NTI is a nonprofit, nonpartisan group working to reduce global threats from nuclear, biological, and chemical weapons.