" if they brush aside treaties and international laws, tension rises and wars ensue"
To secure the Soviet Union's agreement on Germany's reunification, James Baker made a verbal agreement to Michael Gorbachev that NATO will not move "one inch Eastward". Bill Clinton summarily dismissed that commitment. The following twelve nations joined NATO since the fall of the Soviet Union: The Czech Republic, Hungary, Poland, Bulgaria, Estonia, Lithuania, Romania, Slovakia, Slovenia, Albania, Croatia and Montenegro
In December 2001, George W. Bush unilaterally withdrew from the ABM Treaty of May 1972 on strategic arms limitations. On May 8th, 2018, Donald Trump unilaterally pulled out of the JCPOA, signed on July 14th, 2015 after 10 years of laborious negotiations with Iran. In October 2018, Donald Trump revoked the INF Treaty under the pretext that Russia didn't abide by its commitments while the United States was installing anti-missile bases in Poland and in Romania, supposedly to protect Western nations from Iran's missiles. That move was interpreted by Vladimir Poutine as an obvious violation of the Treaty.
In the Spring of 2018, the United States, Great Britain and France launched a missile attack against Syria on the basis of unsubstantiated claims that Bashar al-Assad was using chemical weapons against his people.
That same year, the United States started a trade war with China in violation of the rules of the World Trade Organization which require that disagreements be submitted to an arbitrage court. Needless to say, that China itself swindled the WTO rules in the past.
This July, Great Britain boarded and searched an Iranian ship near Gibraltar in defiance of international laws.
A few days ago, India revoked Article 370 of its constitution to annex the Jammu-and-Kashmir province in retaliation for Pakistan crossing the Line of Control a line which serves as de facto border. This dispute between two nuclear powers goes back to 1947 when India and Pakistan won their independence from Great Britain.
China is slowly but surely taking control of the South China Sea the same way the United States control the Gulf of Mexico.