U.S. and China trade tensions are likely to continue and make trouble for markets after the G-20 summit, expects Marie Owens Thomsen, global chief economist at Indosuez Wealth Management. "The Congress has given executive authority to the president to negotiate without necessarily asking the Congress each and every time, and as long as that sort of delegated power sits with the president, I feel it (trade) will continue to be a theme as we go forward," Thomsen told CNBC's Nancy Hungerford. "Unfortunately, I think that in all probability, trade will continue to be one of the favorite battle horses of this administration." Thomsen said a trade agreement between the U.S. and China is essential to stock markets and the world economy.

Tit-for-tat on tariffs

As the G-20 finance leaders meet to discuss global policies in the Argentine capital of Buenos Aires on Nov. 30 and Dec. 1, one of the most pressing challenges will be the trade tariff dispute between the US and China. Regardless of the outcome, the meeting between U.S. President Donald Trump and his Chinese counterpart Xi Jinping is likely to affect the future of Sino-U.S. relations and global trade. Expectations of a trade deal are tempered after Trump complained of unfair trade practices and imposed 10 percent tariffs on $200 billion of Chinese imports in September. China retaliated by imposing taxes on $60 billion worth of U.S. products.

Trade will continue to be one of the favorite battle horses of the U.S. administration. Marie Owens Thomsen global chief economist, Indosuez Wealth Management