The trend was also noted in a report released in November by ForwardKeys, a European travel research agency. It found that weekly bookings from China to the US rose by 2 percent from the last week of February to March 23 last year, when the first tariffs imposed in the trade war took effect. Since then, the year-on-year figure to November fell by 7.2 percent, reflecting the escalation of trade tensions and the announcement of new tariffs by the two countries.

The negative impact on the yuan, which has fallen by 8.7 percent against the US dollar since tariffs were introduced－meaning that Chinese tourists' money buys less－and warnings from Beijing about US travel security risks, have likely further influenced the trend, the report said.

Significant impact

ForwardKeys CEO and cofounder Olivier Jager said the company's findings strongly suggest that the trade war has had a significant impact on Chinese tourism to the US. "We estimate that the cost to the US economy will be north of half a billion dollars in 2018. Chinese spending in this sector is significant－it amounts to the largest category of US services exports to China," he said.

David Tarsh, a spokesman for the company, said the majority of Chinese outbound tourists visit countries in Asia such as Japan or South Korea, and fewer than 10 percent of them venture as far as the Americas.

He said Chinese outbound tourism is "very healthy", with this market growing from January to April.

"America is actually losing business, compared with the same first four months of last year, and that's in the context of travel to other parts of the world from China rising," he said.

"So if you are responsible for attracting Chinese to the Americas, you wouldn't be feeling very pleased with yourself," he added.

Christopher Heywood, executive vice-president at NYC & Company, the official tourism marketing organization for New York City, noted an 11.9 percent decline in spending from Chinese travelers during the first quarter of this year.

"We understand that the Chinese government first of all has issued some warnings, (about) frequent shootings, and also they've issued, I think, a warning that visa processing is taking longer. But more than anything, we are concerned about the trade war in general, and just what that's doing to the economy, and whether that's restricting travel and deterring people from coming to the US," Heywood said.

China is an important and lucrative market for New York, Heywood added. Chinese travelers comprise the second-largest international market for the city, behind the United Kingdom.

In 2016, New York welcomed 951,000 Chinese visitors, a 9.3 percent rise from 2015. In 2017, the city received 1,038,000 Chinese, surpassing 1 million visitors for the first time.