The Trump administration had indicated it was ready to move ahead with a next round of tariffs after the end of a public comment period, which finished at midnight in Washington on Thursday, but the timing is uncertain, people familiar with the administration's plans said.
Trump acknowledged in a tweet that "Apple prices may increase because of the massive Tariffs we may be imposing on China", but suggested the issue was not with the tariffs themselves. "To a certain extent it's going to be up to China", Trump said.
But he told reporters traveling with him to Fargo, North Dakota that "behind that, there's another $267 billion ready to go on short notice if I want".
A package of tariffs worth $200bn is close to being imposed on Chinese imports to the U.S. and Trump's latest suggested round - which would be worth $267bn - would sharply escalate Trump's trade war with China.
In a Saturday morning tweet, Mr. Trump said that if Apple wants to avoid tariffs on its products, it should make those devices in the USA rather than China.
"Our concern with these tariffs is that the USA will be hardest hit, and that will result in lower U.S. growth and competitiveness and higher prices for United States consumers", Apple said in its letter.
White House economic adviser Larry Kudlow just hours before said talks with Beijing were continuing to try to defuse the conflict, and that he was hopeful that a solution could be found. "Lower barriers, open markets, quit stealing IP and technology", he said, using an abbreviation for intellectual property.
Washington is demanding Beijing improve market access and intellectual property protections for USA companies, cut industrial subsidies and slash a $375 billion trade gap.
"There is still an impact from front-loading of exports, but the main reason (for still-solid export growth) is strong growth in the USA economy", said Zhang Yi, an economist at Zhonghai Shengrong Capital Management.
At the same time, Apple is already using components sourced from USA manufacturers in some of its products.
While China's trade surplus with the United States grew again, it remained stable with the rest of the world at US$27.9 billion in August.
"More broadly, tariffs will lead to higher US consumer prices, lower overall USA economic growth, and other unintended economic consequences". And China has vowed to hit $60bn in U.S. products in retaliation.
"We are puzzled as to why the Administration may be using tariffs in part to re-engineer global ICT (information, communication and technology) supply chains that have served USA companies so well".
He added: "We've taxed them $50 billion that's on technology".
Mr Trump imposed customs duties of up to 25 per cent on US$34 billion worth of Chinese goods in July, and on another US$16 billion in August, triggering swift tit-for-tat responses from Beijing.