President Donald Trump says he is considering some "very severe things" to respond to North Korea's test launch of an intercontinental ballistic missile.
But he added that that does not mean he would follow through on them.
Speaking at a joint news conference with Polish President Andrzej Duda in Warsaw on Thursday, Trump said he wanted to look at what happens over the coming weeks and months and called North Korea's behaviour "a shame".
He said North Korea was behaving in a "very, very dangerous manner" and that something would have to be done about it.
READ MORE: US - Ready to use force in North Korea 'if we must'
North Korea launched the missile earlier this week.
Al Jazeera's James Bays, reporting from Warsaw, said the issue shall be a topic of discussion when Trump meets with world leaders in Germany later this week.
"Expect a bit of a difficult meeting with China's President Xi Jinping because President Trump had put a lot of his eggs in the China basket in dealing with North Korea.
"Trump hosted Xi at his Mar-a-Lago resort in Florida in April, where relations between the two countries looked good.
"Trump even talked about serving Xi a wonderful chocolate cake. Well, the chocolate cake clearly didn't get the results that President Trump hoped because he certainly has been tweeting that China has not been doing enough to pressure North Korea," Bays said.
On Wednesday, Nikki Haley, the US' ambassador to the UN, said the US may use military force to defend the country and its allies against North Korea if necessary, but said it prefers to use its clout in international trade to address what she said was a growing threat.
In a hard-hitting speech at an emergency meeting of the UN Security Council after Pyongyang's successful launch of an intercontinental ballistic missile (ICBM), Haley said that "the world has become a more dangerous place" and China has a key role in promoting peace.
China is responsible for 90 percent of trade with North Korea and Haley warned that Beijing risks its massive trade with the US if its business dealings with Pyongyang violate UN sanctions.
She said the US doesn't seek conflict - "in fact we seek to avoid it".
But she said the launch of an ICBM "is a clear and sharp military escalation" and the US is prepared to use its "considerable military forces" to defend itself and its allies "if we must".
But Haley said the Trump administration prefers "not to go in that direction" but to use its "great capabilities in the area of trade" to address "those who threaten us and ... those who supply the threats."
