Ahead of summit talks between U.S. President Donald Trump and Prime Minister Shinzo Abe scheduled for later this week, the Trump administration is upping its efforts to reassure Japan of its security commitment to the county.

During a telephone conference Tuesday, U.S. Secretary of State Rex Tillerson told Foreign Minister Fumio Kishida that Article 5 of the Japan-U.S. security treaty applies to the Japanese-controlled Senkaku Islands, which are also claimed by China and Taiwan, where they are known as the Diaoyus and Tiaoyutai, respectively.

The Senkaku remarks were the first time Tillerson had mentioned Article 5 since he was sworn in as top U.S. diplomat last week. Article 5 states that the U.S. and Japan will act together in the event Japanese administered territories are attacked. The former Exxon Mobil Corp. CEO had laid out a similar position during his confirmation hearings last month.