When it comes to Taiwan, China’s generals say they are simply following the example of U.S. President Abraham Lincoln.

China’s Defense Minister Wei Fenghe on Sunday invoked Lincoln’s efforts during the U.S. Civil War to justify Beijing’s approach toward Taiwan, which it sees as an integral part of its territory that must be unified by force if necessary.

“American friends told me that Abraham Lincoln was the greatest American president because he led the country to victory in the Civil War and prevented the secession of the U.S.,” Wei said on Sunday at the Shangri-La Dialogue, a security conference in Singapore. “The U.S. is indivisible, so is China. China must be and will be reunified.”

Taiwan’s Ministry of National Defense said in a statement Monday that Wei’s remarks “highlight the Chinese communists’ nature of wantonly engaging in military aggression and impose a serious threat to peace and security in Taiwan Strait and in the region.”

Tensions over China and Taiwan have increased in recent months, with the U.S. regularly sailing warships through the Taiwan Strait. The Trump administration has defended the moves as demonstrations of free passage allowed by international law, while China sees them as provocations.

The U.S. is obligated to sell “arms of a defensive character” to Taipei under the 1979 Taiwan Relations Act. Trump administration officials have given tacit approval to Taipei’s request to buy more than 60 Lockheed Martin Corp. F-16s, Bloomberg reported in March, prompting a fresh protest from China.

Wei said that China could “find no justifiable reasons” for the U.S. to get involved with Taiwan through its domestic law.

“No attempts to split China shall succeed,” he said, adding that “foreign intervention in the Taiwan question is doomed to failure.”