Washington: US President Donald Trump Monday announced imposing new tariffs on an additional USD 200 billion worth of imports from China, escalating the trade war with the Asian giant.

Alleging that China has been unwilling to change its unfair trade practices, Trump said the new additional tariff structure would be effective September 24 from when it would be at 10 percent until the year end, but would increase to 25 per cent level from January 1.

Further, if China takes retaliatory action against our farmers or other industries, we will immediately pursue phase three, which is tariffs on approximately USD 267 billion of additional imports, Trump said in a strong warning to China.

Trump said his administration is taking this action as a result of the Section 301 process that the USTR has been pursuing for more than 12 months. US Trade Representatives (USTR) released a list of such items.

After a thorough study, the USTR concluded that China is engaged in numerous unfair policies and practices relating to United States technology and intellectual property  such as forcing United States companies to transfer technology to Chinese counterparts, he said.

These practices plainly constitute a grave threat to the long-term health and prosperity of the United States economy, he added.

For months, we have urged China to change these unfair practices, and give fair and reciprocal treatment to American companies. We have been very clear about the type of changes that need to be made, and we have given China every opportunity to treat us more fairly, he said.

But, so far, China has been unwilling to change its practices, he said.

To counter China's unfair practices, he had announced on June 15 that the US would impose tariffs of 25 percent on USD 50 billion worth of Chinese imports.

China, however, still refuses to change its practices and indeed recently imposed new tariffs in an effort to hurt the United States economy, Trump said.

China, he said, has had many opportunities to fully address US concerns. ‘I urge China's leaders to take swift action to end their country's unfair trade practices. Hopefully, this trade situation will be resolved, in the end, by myself and President Xi of China, for whom I have great respect and affection,’ Trump said.

Later a senior administration official told reporters that China has had many opportunities to change those practices and, in fact, the statute says that trade representatives shall take all appropriate and feasible action in an effort to obtain the elimination of those practices.

So we've negotiated and negotiated and negotiated and given them chance after chance after chance... The administration has imposed tariffs on roughly USD 50 billion worth of Chinese imports already, in an effort to encourage China to alter its behaviour, the official said.

By imposing such a tariff, the official said, the US is not trying to constrain China's growth.

We have no problem with China trying to grow its economy, trying to lift its people out of poverty, that's a good thing. But, in doing so, they can't take actions that deliberately discriminate against other countries; actions that hurt American workers. And they can't take actions that entirely flout the rules of the international trading system, the official said.

Such a move, the official said, is not an effort to constrain China.

But this is an effort to work with China and say, it's time that you address these unfair trading practices that we have identified, that others have identified, and which have harmed the entire global trading system, the official asserted.

At the same time, the official said, the US remains open to negotiations.

We don't have anything to announce to you today, in terms of any of the logistics of that, but, as the President has said, we are open to that and we hope that China will come to the table and address the concerns that we have raised, the official said.

House Ways and Means Committee Chairman Kevin Brady said Trump is clearly increasing the pressure on China to come to the table and begin a new trading relationship that is fairer to the American farmers, workers and businesses.

The sooner President Xi and President Trump meet to craft a new trade path forward, the better,he said.

There is no disagreement between the Congress and the President that we must hold China accountable for hurting the US companies and workers on a colossal scale by extorting our companies to transfer their best technology, stealing our intellectual property, and shoring up China's state-run companies through subsidies and other distortive practices, Brady said.

Any time tariffs are imposed, I worry that Americans will be forced to pay extra costs - in this case on nearly half of the US imports from China, he said.