Australia will join the United States in a coalition of countries protecting oil tankers and cargo ships from threats posed by Iran in the Strait of Hormuz, Prime Minister Scott Morrison said on Wednesday.

Morrison said Australia will send a P-8A Poseidon surveillance plane to the Middle East for one month before the end of 2019, 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 Iran and the West.

Global commodity trading has been rocked in recent months after a series of Iranian attacks on international merchant vessels and the seizure of a British tanker in the Strait of Hormuz, a narrow waterway through which almost a fifth of the world’s oil passes.

“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,” he said.

Washington, which has by far the strongest Western naval contingent in the Gulf, has been calling for its allies to join it in an operation to guard shipping.

However, European countries, which disagree with a US decision to impose sanctions on Iran, have been reluctant to sign up to a US-led mission for fear of adding to tension in the region.US President Donald Trump withdrew Washington in 2018 from an international deal to curb Iran’s nuclear ambitions.