New York (CNN Business) Dow ( INDU ) futures were lower ahead of Monday's opening on Wall Street. Investor braced for the fallout of continuing global trade tensions.

China on Friday retaliated with new tariffs on American imports after the Trump administration raised tariffs on Chinese goods. Also on Friday, President Donald Trump announced the United States would remove India from a special trade program . And investors are still trying to determine how new tariffs on Mexico might affect American businesses and the economy.

The sudden, unexpected expansion of tariffs have rattled Wall Street.

The Dow tumbled below 25,000 points to four-month lows on Friday. The Dow and S&P 500 each declined nearly 7% in May, their first losing months since December. The Nasdaq tumbled 8% on the month, its worst May since 2010.

Nikkei N225 Shanghai Composite SHCOMP S&P 500 SPX Nasdaq COMP Tokyo'sclosed down 0.9%, while thedeclined 0.3%. Benchmark indexes in London and Paris dipped 1% in early trading. Dow futures were down about 70 points or less than 0.3%.futures were also down 0.3%.futures fell 0.4%.

Fiat Chrysler FCAU General Motors GM Ford F Trump's threat to impose escalating tariffs on Mexico, one of America's largest and most important trading partners, amplified fears about slowing economic growth. The United States imported $346 billion of goods from Mexico last year, including everything from auto parts and avocados to beer and televisions. Automakers, includingand, rely on Mexico as a vital part of their supply chain.

Amazon AMZN Walmart WMT Google GOOGL Facebook FB Netflix NFLX Uber UBER Disney DIS And India is an important trading partner for the United States too. Access to India's population of 1.3 billion people is crucial for American businesses, with big names likeandinvesting billions of dollars in the country in recent years. India's 600 million internet users — more than any country except China — are also a big draw forand

Wall Street has already been shaken by the trade war with China. The growth in tariffs are beginning to take an effect on the Chinese economy: Activity in China's vast factory industry fell to a three-month low in May. New orders declined, likely reflecting pressure from the trade war.