Prime Minister Malcolm Turnbull has met with high level security officials in Washington to discuss progress in the battle against Islamic State (IS).

Mr Turnbull met with Defence Secretary Ash Carter, the head of the CIA and the director of National Intelligence at the Pentagon to discuss a number of issues including cyber-security and ground combat in Syria.

The Prime Minister emerged from the talks looking optimistic and said he was looking forward to further gains against terrorist group in the next six months or so.

“There is a very real prospect of the defeat of Daesh in the battlefield, ending their so-called caliphate,” Mr Turnbull said, using another name for IS.

Later today Mr Turnbull will meet with Paul Ryan, the Speaker of the US House of Representatives, as he seeks to convince US politicians of the benefits of the Trans Pacific Partnership (TPP) trade deal.

The TPP is controversial in the United States, but there is an opportunity for it to be passed.

The TPP — the largest regional trade accord in history — requires congressional approval but is controversial in the US where many opponents see free trade as a threat to domestic jobs.

PM talks census debacle

In a speech to the Centre for Strategic and International Studies in Washington DC on Friday morning (AEST), Mr Turnbull said Australia struggled with the meaning of the word “attack” after the denial of service incident that led to the census website being shut down on census night.

The census was a disaster for the ABS and those trying to complete it online. Photo: AAP

“If a nation state says that it has come under attack, the meaning, and therefore the act itself, is weighted with tremendous significance,” he said.

“We need to be able to communicate an accurate level of significance.”

The public needed to know that a denial of service was equivalent to having a bus block a driveway so a car couldn’t get out, while a hack meant someone breaking into a garage and stealing the car, Mr Turnbull said.

“If we hear of an air disaster involving a cabin fire or an engine fire on an aircraft, we understand the difference between, and different implications of, those two scenarios,” he said.