While prime minister-designate Boris Johnson moves into 10 Downing Street, a British tanker captured by Iran isn't going anywhere, a headache for the newcomer. How will Johnson navigate the waters amid rising tensions in the Persian Gulf. Will a "personal equation" between Donald Trump and Johnson change the UK's policy towards Iran?

The issue of safe passage in the gulf region came up during public debates between Johnson and his rival candidate earlier this month. Many people were concerned whether Johnson's aim to curry favor with the U.S. would affect his ability to follow through on the UK's own commitment to the fragmenting Iran nuclear accord, which Johnson said he wants to stick to despite its fragile past.

While many draw comparisons between Trump and Johnson, the incoming UK prime minister has called for a diplomatic solution to the crisis: a sentiment shared by Iran. Iran's foreign minister also tweeted his congratulations to Johnson but tempered that with a warning that Tehran would protect the Gulf's waters.

Earlier, Britain proposed an idea for a European-led naval mission to ensure safe shipping through the Strait of Hormuz and got support from France, Italy, the Netherlands and Denmark.

The UK and Iran are taking a two-pronged approach, with British Foreign Secretary Jeremy Hunt saying the UK will spearhead efforts to tackle what they're calling "state piracy."