Vice-President Mike Pence visited the Korean demilitarized zone on Monday, a day after the failure of the North Korean missile test. The US and South Korea said that the rocket exploded during launch.

Standing within 60 meters (200 feet) from the North Korean border, Pence called the DMZ "the frontier of freedom" and added that "all options are on the table" aimed at the denuclearization of the Korean Peninsula. Tensions on the Peninsula intensified in recent weeks, due to the fact that the US and North Korea rattled the saber, and warning analysts that North Korea is preparing for another nuclear test.

Demilitarized zone (DMZ) is a strongly fortified border between North and South Korea. It stretches for 250 kilometres (160 miles) and is dotted with military posts, mines and protective structures. Repeating the words of U.S. Secretary of state Rex Tillerson last month, Pence said that "the era of strategic patience is over."

United States relied on China, the main ally of North Korea to exert pressure on Pyongyang to constrain its nuclear ambitions. At the same time, it increased its military footprint in the region, deploying a naval battle group of carriers in the waters of the Korean Peninsula.

The President of the United States Donald trump earlier this month held a summit with Chinese President XI Jinping and praised the return of China to the North Korean coal vessels as a "big step" forward in the effort to enlist China's support against Pyongyang.

According to Pence on Monday trump is "very hopeful that China will take actions aimed at policy change in North Korea, to renounce its programme of creating nuclear weapons programs and ballistic missiles."

Speaking on Sunday, Advisor to the President for national security H. R. McMaster said, when it comes to North Korea's nuclear program, "all our options are on the table that are subject to improvement and further development". He stressed that the United States hope not to use military force, but warned that "this problem comes to a head."

McMaster said a variety of military and US intelligence services are working on providing options to "prepare them" for trump, "if this model of destabilizing behaviour will continue." On Friday, North Korea said that the dangerous security situation was caused by "reckless military provocation of the administration of the trump."
sections: Politics, World News, Accidents