Australian PM says it’s within country’s ‘national interest’ to work with US-led security mission.

Australia has joined the United Kingdom and Bahrain in signing onto a US-led maritime security mission that the United States said is aimed at protecting international shipping in the Strait of Hormuz.

Prime Minister Scott Morrison said on Wednesday that Australia will contribute troops, a surveillance plane and a frigate to protect shipping lanes off the coast of Iran.

“This destabilising behaviour is a threat to Australia’s interests in the region,” Morrison said at a conference in Canberra.

“The government has decided that it is in Australia’s national interest to work with our international partners to contribute. Our contribution will be limited in scope and it will be time-bound.”

Morrison said Australia will send a P-8A Poseidon surveillance plane to the Middle East for one month before the end of the year, while an Australian frigate will be deployed in January 2020 for six months.

Australia’s deployment will expand US-led efforts to secure the strait, which lies between Oman and Iran, after tensions spiked between Tehran and the West.

The US claims the mission is needed to “combat Iranian aggression” in the strategic waterway, and has been looking for allies for the naval coalition.

At least 15 percent of crude oil and up to 30 percent of refined oil destined for Australia transits through the Gulf.

The friction is rooted in US President Donald Trump‘s decision in May 2018 to unilaterally withdraw from a landmark nuclear deal signed in 2015 between world powers and Iran.

Since then, the US has reinstated sweeping sanctions against Tehran as part of a “maximum pressure” campaign and has also beefed up its military presence in the region.

The tensions escalated in May, when the US accused Iran of sabotaging tankers in the shipping route, allegations denied by Iran.

UK’s Ministry of Defence announced this month that Royal Navy vessels will work alongside the US Navy to escort vessels through the busy strait.

Britain has been giving UK-flagged vessels a naval escort since Iran’s Islamic Revolutionary Guard Corps (IRGC) seized a British oil tanker last month. The move followed the seizing of an Iranian oil tanker off the coast of Gibraltar in July.

Earlier this month, Germany ruled out participating in the US-led mission, prompting a frustrated response from US officials.

Last week, Iran warned Israel against supporting the mission, saying it reserved the right to confront a “clear threat”.

In June, Iran downed a US military surveillance drone in the Gulf with a surface-to-air missile. Iran says the drone was in its airspace, but Washington says it was in international skies.

Trump said at the time he had been prepared to attack three Iranian targets in retaliation but called off the operation at the last minute because such a response would not have been “proportionate”.