President Dwight David “Ike” Eisenhower addressed the nation on February 20, 1957, regarding the Suez Crisis.
 
“We do, however, believe that upon the suppression of the present act of aggression and breach of the peace, there should be a greater effort of the United Nations and its members to secure justice and conformity with international law. Peace and justice are two sides of the same coin. Perhaps the world community is at fault for not having paid enough attention to this basic truth.”
 
Although Eisenhower coined the saying and is widely quoted for it, the concept that peace and justice are connected has been said to date back to at least the time of the ancient Greek philosophers, such as Plato.
 
   
Wikipedia: Dwight D. Eisenhower
Dwight David “Ike” Eisenhower (pronounced /ˈaɪzənhaʊər/, eye-zən-how-ər; October 14, 1890 – March 28, 1969) was the 34th President of the United States from 1953 until 1961. He had previously been a five-star general in the United States Army during World War II, and served as Supreme Commander of the Allied Forces in Europe; he had responsibility for planning and supervising the invasion of North Africa in Operation Torch in 1942–43 and the successful invasion of France and Germany in 1944–45, from the Western Front. In 1951, he became the first supreme commander of NATO.
   
21 February 1957, Cleveland (OH) Plain Dealer, pg. 12, col. 4:
Text of Eisenhower’s Speech on Crisis in Middle East
Problem Raised by Israel’s
Refusal to Withdraw Her
Troops; Issue Vital to Us
WASHINGTON, Feb. 20 (AP)—Here is the text of President Eisenhower’s radio-television address to the nation tonight on the Middle East situation.
(...)
Basic Pledge of the U.N. Is to Renounce War
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We cannot consider that the armed invasion an occupation of another country are “peaceful means” or proper means to achieve justice and conformity with international law.
 
We do, however, believe that upon the suppression of the present act of aggression and breach of the peace, there should be a greater effort of the United Nations and its members to secure justice and conformity with international law. Peace and justice are two sides of the same coin.
 
Perhaps the world community is at fault for not having paid enough attention to this basic truth. The United States, for its part, will vigorously seek solutions of the problems of the area in accordance with justice and international law.
   
Google Books
Social Justice Handbook:
Small Steps for a Better World
By Mae Elise Cannon
Downers Grove, IL: IVP Books
2009
Pg. 24:
In early antiquity the philosophers believed that peace and justice were two sides of the same coin. The early Greek philosopher Plato argued in the Republic that justice was “peace” or harmony.
 
Google Books
The World’s Religions After September 11
By Arvind Sharma
Westport, CT: Praeger Publishers
2009
Pg. 166:
This view of the use of force is consistent with the scriptures’ recognition that peace and justice are two sides of the same coin; true peace cannot exist without justice, and justice may require the use of some kind of force. 
   
studymode
Two Side of the Same Coin: Justice and Peace
By melduard14, Dec 2010
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There is a saying also about justice that says “Peace and justice are two sides of the same coin.” This means even though something may look or seem different to another thing they are both the same.
 
Google Books
Global Peace Lovers
By Aasef Shafik
Bloomington, IN: AuthorHouse
2011
Pg. 470:
“Peace and justice are two sides of the same coin.” – Dwight D. Eisenhower