The Coalition’s rhetoric on China has dramatically escalated on Anzac Day, with Defence Minister Peter Dutton saying Australia should "prepare for war" to preserve the peace.

Prime Minister Scott Morrison on the weekend said China building a military base in the Solomon Islands would be a "red line" for Australia, but did not say what Australia would do in the event a military base was built.

Labor’s defence spokesman Brendan O’Connor said the opposition would be seeking a briefing from the government given the shift in the government’s message and tone.

But he labelled the government’s "post-facto rhetoric" on the deal between the Solomons and China as too little too late, saying the Coalition should have done more to engage with the Solomons before its deal with China was signed.

Today on Please Explain, political and international editor Peter Hartcher joins Bianca Hall to discuss the increasing role China is playing in Australia’s domestic election campaign.