BRUSSELS, July 10 (Xinhua) -- U.S. President Donald Trump continued to criticize European allies on the eve of the North Atlantic Treaty Organization (NATO) summit in Brussels.

Trump arrived in Brussels on Tuesday evening for the NATO summit scheduled for Wednesday and Thursday, after which he is expected to visit Britain and later meet Russian President Vladimir Putin in Finland's capital Helsinki.

"The European Union makes it impossible for our farmers and workers and companies to do business in Europe (U.S. has a 151 billion dollar trade deficit), and then they want us to happily defend them through NATO, and nicely pay for it. Just doesn't work!" Trump tweeted on Tuesday evening.

"Many countries in NATO, which we are expected to defend, are not only short of their current commitment of 2 percent (which is low), but are also delinquent for many years in payments that have not been made. Will they reimburse the U.S.?" he wrote in another tweet earlier in the evening.

The two tweets represented two major topics of criticism Trump has long held against U.S. allies across the Atlantic: one is his belief that the European Union erected trade barriers against the U.S. and as a result won surplus in the trade of goods, and the other that European members of NATO are not spending enough on defense.

Prior to boarding Air Force One for Europe, Trump already took jabs at European allies by other tweets, including "NATO countries must pay MORE, the United States must pay LESS. Very Unfair!"