How can the United States handle North Korean threat?

Pentagon now view North Korea as the biggest threat to the security of United States, having conducted about 14 missile tests in this year alone, and openly threatening the United States of nuclear attack.

North Korea’s threat is in response to the US’s threat of military action against North Korea’s missile and nuclear tests.

The US administrations from Obama to Trump, have committed a series of mistakes on containing North Korea.

A series of sanctions for the past one decade has led North Korea to face severe economic crisis, and forced it to the wedge of “feeling nothing more to loss”, but to fight back by any means.

North Korea has the backing of China, and Russia. As China is reluctant to abandon its age-old ally, just to please the United States for some economic gains. Another bricking point is that, China doesn’t like US forces on its doorsteps, as it has already complained about the deployment of THAAD missile defense system in South Korea.

South China Sea issue has already has raised tension between the United States and China.

  Russia is another influential player in the region, which has a cordial relationship with North Korea, and Russia voluntarily announced its willingness to mediate in the North Korean issue, but the US simply ignored it missing a golden opportunity to solve the North Korean issue in a mutually amicable way, and made the situation still worse.  

It should be noted that before the entry of Russia in the Syrian conflict, the situation in Syria was a total mess. Former President Barrack Obama openly declared the lack of clear policy on Syria, but Russians have achieved a ceasefire, and stabilized the Syrian government.

Another series of sanctions on Russia, on the allegation of annexation of Crimea, as well as meddling in US presidential election, led a wide gap between the United States and Russia; some analysts call this as another cold war. In retaliation for the sanctions, any Russian help to North Korea and Iran to miniaturize nuclear weapons will make the United States security in grave danger.

Neither the White house nor the pentagon have a clear policy to tackle North Korea, why cannot let the Russians to try?