He is the only Asean leader who will be addressing the conference, which runs alongside the Australia-Asean Special Summit.
Southeast Asian leading figures have declared their aspiration for a quick settlement with China to be secured for a new South China Sea code of conduct.
President Donald Trump announced the tariffs on March 7 to protect domestic steel and aluminium producers on national security grounds.
Lee and Turnbull urged ASEAN to put its weight behind the Regional Comprehensive Economic Partnership, a China-backed alternative to the Trans-Pacific Partnership (TPP) trade pact.
Major ASEAN states such as Indonesia are likely to use the forum to push for Australia to be invited to apply for full membership in the organisation.
The prime minister said the legislation had saved numerous lives, both Malaysians and non-Malaysians, and that he was proud to say that not one single terrorist outrage leading to loss of life had been committed on Malaysian soil.
The issue was driven home a year ago when pro-Daesh militants seized the southern Philippine city of Marawi, with Australia aiding Manila to win it back.
"I am conscious of this new set of dynamics causing regional neighbours to brush up their linkages, and I think it is well worth examining".
Serial bomber suspected in deadly Austin explosions, say police
Bryce Dubee, an Iraq and Afghanistan army war veteran, likened the feeling to his fear of IEDs. "That's what made me feel sick". He said the technicians and canine will assist Austin police and the Federal Bureau of Investigation as long as they're needed.
ASEAN countries agreed to work closely to provide humanitarian assistance to Rohingya refugees.
But while a final communique noted a resolve to "protect the human rights of our peoples", it failed to condemn member state Myanmar's treatment of the Muslim-minority Rohingya.
"But together, we will be safer", he said in his keynote address at the closing ceremony of the Counter-Terrorism Conference held at during the International Conference Centre (ICC) Sydney here Saturday.
"It is in our interest to engage all ASEAN members including Aung San Suu Kyi at this summit because it gives us the best chance of influencing outcomes and making our concerns known, so these are matters that we would be discussing with the Myanmar delegation", Bishop said.
"It's a very complex problem. Everyone seeks to end the suffering that has been occasioned by the events, the conflict, the dislocation, the displacement of persons".
Remarking on a recent case in which extremists in Syria used an encrypted messaging platform to pass weapon-building instructions into Australia almost undetected, Mr Turnbull said "the frontline in this battle against terrorism in this interconnected world is everywhere".
"Australia would be happy to be able to have it waived for every other single country in the world - in other words, for the U.S. to withdraw from this particular initiative", he said. You can sign up to receive it directly here.