U.S. President Barack Obama says deep bonds and a common purpose strengthen the alliance between the United State and Australia.

Mr. Obama commended the sacrifice made by U.S. and Australian troops soldiers during a visit Thursday to a military base in Darwin, where U.S. forces will soon be stationed under an agreement to maintain a military presence on Australian soil.

He said Darwin — where forces from the two countries died together during a Japanese attack in World War II — is the perfect place for the two nations to deepen their ties.

Mr. Obama said the purpose of their alliance is the preservation of peace and security. He also reminded the troops of the importance of their presence in the region.