Iran is keen to test the Royal Navy’s resolve as it escorts UK-flagged commercial shipping through the contested waters of the Strait of Hormuz, the commander of a British warship said Wednesday.

William King, commander of HMS Montrose, said during 27 days patrolling the flashpoint entrance to the Gulf he and his crew experienced 85 “interactions with Iranian forces”, which had often led to “an exchange of warnings” over radio.

“That gives you some idea of the intensity… (it) is perhaps more than we’ve seen of recent times,” he told BBC Radio in a satellite phone interview from aboard the frigate. “The Iranians seem to be keen to test our resolve, test our reactions most of the time,” King added.

“They’ll claim that perhaps our presence is illegitimate, even though we’re completely lawfully in international waters. They may also run boats in at speed towards us, to test what warning levels we get to.”

Montrose is in the area as part of a three-year deployment based at a British naval hub opened in Bahrain last year. The warship began the escorts through the world’s busiest oil shipping lane earlier this month.

Plans for the ship to be joined by other elements from European navies is still a matter of debate.

Iran Slams UK Proposal for European Naval Mission in Gulf as ‘Hostile’ https://t.co/sRwm1K9Y2Y — Breitbart London (@BreitbartLondon) July 28, 2019

Royal Navy involvement followed Iranian threats of retribution for Royal Marines helping Gibraltar — a British Overseas Territory — seize one of its tankers on July 4 on suspicion it was carrying oil to Syria in violation of E.U. sanctions.

Despite Montrose’s presence in the Gulf, Iran intercepted the British-flagged tanker Stena Impero on July 19 as it made its way through the strait and has detained the ship at an Iranian port.

Despite the escalating tensions, King said contact with Iran remained “professional” and “cordial” at all times.

“There’s a healthy understanding, shall I say a respect between mariners, which now seems to be established,” he added.

Montrose will return to port later this week for pre-planned maintenance and crew changeover. She was replaced by the Type 45 destroyer HMS Duncan which arrived in the region on Sunday.

Defence Secretary Ben Wallace said the Royal Navy will continue to escort U.K. vessels until a diplomatic resolution is found to secure the route again.

The UK is to send two more ships to the region later this year, according to Forces News. Type 23 frigate HMS Kent will take over from HMS Duncan, supported by RFA Wave Knight.

HMS Montrose, also a Type 23 frigate, will remain stationed in the Middle East until 2022.

The deployments are part of Operation Kipion – the name given to British forces in the Gulf and the Indian Ocean.

AFP contributed to this story