The U.S. military said on Monday it had staged bombing drills with South Korea, flying a pair of B-1B bombers and F-35 fighter jets over the Korean peninsula, in a show of force against North Korea.
The tension on the Korean peninsula has intensified since last Friday, North Korea once again launched a ballistic missile over Japan.
Pyongyang has launched dozens of missiles, in an accelerated weapons program, created to reach an "equilibrium" of military force with the United States, according to The North.
Washington has repeatedly urged Beijing to do more direct actions to rein in Pyongyang, while China - North Korea's main ally - says the USA should refrainshould refrain from issuing more threats.
"The bottom line is that the missiles, were they to be a threat" either to the United States or Japan, "that would elicit a different response from us".
In an interview with Tasnim, Iran's former ambassador to Beijing Mahdi Safari said China is strongly opposed to the escalation of tensions between the United States and North Korea.
Washington D.C. [U.S.A], September 19: United States Defence Secretary Jim Mattis has said that America has many military options that will completely remove the threat posed by North Korea and also save Seoul from a brutal counterattack, but Pyongyang missiles lack the potential to "directly threaten the American or the Japanese territory".
On Monday, he spoke by phone with Chinese President Xi Jinping and both leaders "committed to maximizing pressure on North Korea through vigorous enforcement of United Nations Security Council resolutions", according to a statement released by the White House. "Rocket Man is on a suicide mission for himself and for his regime".
Asked whether there were any military options the United States could take with North Korea that would not put Seoul at grave risk, Mr Mattis said there were, but declined to give details.
Pressed on whether that might include so-called "kinetic" options that use lethal force, Mattis said: "I don't want to go into that".
Mr Mattis also confirmed that he and his South Korean counterpart had recently discussed the possibility of putting USA nuclear weapons back into South Korea, an option that has been raised publicly by some Seoul politicians. Several Pentagon officials say Mattis was not signaling that tactical nuclear weapons are likely to be placed in South Korea.