WASHINGTON (REUTERS) - A top White House economic adviser said on Tuesday (April 23) the United States and China were making progress in trade negotiations and he was "cautiously optimistic" about the prospects for striking a deal.

Speaking at a luncheon at the National Press Club, National Economic Council Director Larry Kudlow said the two nations still had issues to address and were discussing a "visitation exchange" as part of their ongoing talks.

"We're not there yet, but we've made a heck of a lot of progress," Kudlow said in response to questions from reporters."We've come further and deeper, broader, larger-scale than anything in the history of U.S.-China trade."

"We've gotten closer and we're still working on the issues, so-called structural issues, technology transfers," Kudlow added.

"Ownership enforcement is absolutely crucial. Lowering barriers to buy and sell agriculture and industrial commodities. It's all on the table."

Washington and Beijing have engaged in a tit-for-tat trade war that has seen both countries imposing tariffs on billions of dollars' worth of each others' imports.

The United States is seeking structural changes in China's economy, from reducing industrial subsidies to halting forced technology transfers by US companies seeking to enter the Chinese market.