Top Trump administration officials will hold a rare briefing at the White House on Wednesday for the entire US Senate on the situation in North Korea.
A senior Trump administration official said the meeting with senators will take place in the auditorium at the Eisenhower Executive Office Building, the building next to the White House that houses most of the National Security Council.
During a White House lunch with ambassadors of United Nations Security Council member states on Monday, the US president called unacceptable the "status quo in North Korea".
Seemingly everyone has asked, "How could Sean Spicer not have gotten fired yet?" on a near-daily basis ever since he gave his first press briefing as White House press secretary.
Aides, quoted by Reuters, say the House of Representatives is seeking a similar briefing on North Korea.
His phone call came after rumors that Pyongyang could conduct a sixth nuclear test this week.
North Korea hosted its own exhibition of military force Tuesday, according to South Korea's official Yonhap News Agency.
Observers have pointed out that the decision by the Trump administration to summon the entire 100-member Senate to the White House for a briefing is unusual.
On Monday, Trump called for tougher United Nations sanctions on the North, saying it was a global threat and "a problem that we have to finally solve".
Further, U.S. intelligence showed increased activity near North Korea's nuclear test site and Kim Jong Un claimed preparation for a nuclear test is in its "final stage".
South Korean Acting Prime Minister Hwang Kyo-ahn has instructed his military to strengthen its "immediate response posture" in case North Korea does something significant on the April 25 anniversary of its military.
"We feel very confident that the government is not going to shut down", he said.
The conversations involving the president about North Korea took place as a U.S. Navy strike force, led by the aircraft carrier USS Carl Vinson, is approaching the Sea of Japan, off the east coast of the Korean peninsula.
In recent days Ms Haley and other USA officials have underlined China's helpfulness in seeking to increase pressure on the North Korean leader, Kim Jong-un. "And if China and North Korea both believe that President Trump will never allow that to happen, then you have a chance to peacefully solve this", he said.
Trump's intentions for North Korea have remained uncertain, partly by design. China banned coal imports from North Korea in February as part of sanctions against Pyongyang over its nuclear program.
The missile-armed USS Michigan is set to join an incoming group of warships led by aircraft carrier Carl Vinson, which the USA said it was dispatching to North Korea earlier this month to "maintain readiness" in the region.