The North Korean crisis is moving on many fronts.
North Korea conducted a big live-fire exercise on Tuesday to mark the foundation of its military as a U.S. submarine docked in South Korea in a show of force amid growing concern over the North's nuclear and missile programmes.
The USS Carl Vinson has been despatched to Korean waters as a show of strength against Kim Jong-un.
Commentators said that Trump was backing himself into a corner over North Korea.
In this undated photo distributed on Friday, April 14, 2017, North Korean leader Kim Jong Un, center, watches a military drill at an undisclosed location.
The South's Yonhap news agency reported that the exercises were North Korea's largest ever, involving some 300 or 400 pieces of artillery, but the joint chiefs did not confirm the number.
The drill has involved Army, Navy and Air Force. It was not known how he was marking Tuesday's anniversary.
But the timing, as the USA increases its military presence in the area, allows North Korea to remind its opponents that it could cause crippling damage with conventional artillery to highly populated areas in South Korea.
The United States has ordered an aircraft carrier strike group to the western Pacific near North Korea.
As these developments unfolded, Washington was encircling the Korean Peninsula with nuclear-capable warships conducting war games with Japanese and South Korean naval vessels.
But the US shares a substantial amount of the responsibility for returning the nuclear-powered aircraft carrier the USS Carl Vinson back to waters near the Korean Peninsula and for remarks by senior American officials, including US President Donald Trump, about the "military option" and a "preemptive strike".
"North Korea is a big world problem and it's a problem that we have to finally solve", he said.
A meeting of the nuclear envoys of the US, South Korea and Japan in Tokyo resolved the three countries would "take strong punitive action that the North could not bear" if North Korea pushed ahead with another provocative action.
Japan's Foreign Ministry announced that China's envoy for North Korea, Wu Dawei, was arriving in Tokyo on Tuesday for talks with Kanasugi that may take place later this week.
"We need to move more quickly and with greater determination to convince North Korea either to pursue denuclearisation or to apply enough pressure that it stops those activities", Toner told a telephone news briefing. President Trump spoke to Shinzo Abe, Japan's Prime Minister, and Chinese President Xi Jinping over the weekend in an effort to work on a diplomatic solution.
"If you do this kind of ratcheting (up) of rhetorical tensions but also sending military hardware into the region, if you do that absent of any kind of offramp or door or window for the North Koreans to consider walking through and reengaging in any sort of discussions, bad things are going to happen", he added.
Mr Tillerson and US Defence Secretary Jim Mattis will brief the entire US Senate on North Korea on Wednesday, unusually holding the meeting at the White House.
The latest, the 85th anniversary of the founding of North Korea's army, appeared to pass without such a test.
There is also a possibility that North Korea, facing potential changes in regional dynamics as Washington presses Beijing to pressure North Korea more aggressively, opts to mark the anniversary with a missile launch of lesser magnitude.
"If the USA and warmongers run amok with a reckless preemptive strike, we will stage the most brutal punishment of a preemptive attack in the sky and land as well as at sea and from underwater without any warning or prior notice", according to Rodong Sinmun, spokesman of the ruling Workers' Party of Korea.