File photo shows U.S. President Donald Trump (L) welcoming German Chancellor Angela Merkel at the White House in Washington D.C., the United States, on April 27, 2018. (Xinhua/Ting Shen)

WASHINGTON, Dec. 1 (Xinhua) -- U.S. President Donald Trump and German Chancellor Angela Merkel on Saturday exchanged views on trade and security on the sidelines of the Group of 20 (G20) summit in Buenos Aires, according to a statement released by the White House.

The two leaders exchanged thoughts on Russia's violation of the Intermediate-Range Nuclear Forces (INF) Treaty and explored how to strengthen the NATO alliance further as well as how to improve European energy security, the statement said.

They also discussed the ongoing situation of confrontation between Russia and Ukraine, according to the statement.

"We have a great relationship and a great working relationship, I think very important," said Trump before the meeting, according to the statement.

Trump also expressed his praise of Merkel, who "was highly respected by everybody, including me."

Meanwhile, Trump reaffirmed his stance on trade between the United States and Germany, saying that "we have a tremendous trade imbalance, but we're going to get that straightened out."

For her part, Merkel said the two countries should address issues related to fair trade, multilateral issues, the World Trade Organization, the INF Treaty and regional issues concerning Syria and Ukraine.

Despite the long-term alliance between Washington and Berlin, the bilateral ties recently have been overshadowed by their differences on bilateral trade, the Iran nuclear deal, climate change, the defense spending of NATO members and the NORD-Stream 2 gas pipeline project, among other issues.