DUBAI, United Arab Emirates (AP) — A tenuous ceasefire appeared to be holding Saturday after the United States struck two Iranian oil tankers, while the country that hosts the U.S. Navy’s regional headquarters said it arrested dozens of people it alleged were linked to Iran’s Revolutionary Guard.

Friday's attacks cast doubt on the month-old ceasefire that the United States has insisted is still in effect. Washington awaits Iran's response to its latest proposal for a deal to end the war, reopen the Strait of Hormuz to shipping and roll back Tehran’s disputed nuclear program.

The U.S. military said Friday that its forces disabled two Iranian tankers that were trying to breach the American blockade of Iran’s ports. Hours earlier, the military said it thwarted attacks on three Navy ships and struck Iranian military facilities in the strait.

On Saturday, the small Gulf island of Bahrain said it had arrested 41 people it said are part of a group affiliated with Iran’s Revolutionary Guard. The interior ministry said investigations were ongoing but did not provide details.

Bahrain is led by a Sunni Muslim monarchy but, like Iran, has a majority Shiite population. Rights groups have said the kingdom has used the war between Iran and the U.S., which bases its Fifth Fleet in Bahrain, as an excuse to crack down on dissent.

Iran issued a warning to Bahrain. “Siding with the U.S.-backed resolution will bring severe consequences. The Strait of Hormuz is a vital lifeline; do not risk closing it on yourselves FOREVER," Ebrahim Azizi, head of the national security commission of Iran’s parliament, said on social media.

Iran has mostly blocked the critical waterway for global energy since the U.S. and Israel launched the war on Feb. 28, causing a global spike in fuel prices and rattling world markets.

The U.S. has imposed its own blockade of Iran’s ports. U.S. Central Command on Saturday said its forces had turned back 58 commercial ships and “disabled” four since the blockade began April 13.

Britain deploys warship to the Middle East

Britain’s defense ministry said it was deploying a warship to the Middle East to join a potential mission to protect commercial ships in the Strait of Hormuz once hostilities end.

The ministry said the HMS Dragon will “preposition” in the region, ready to join a U.K.- and French-led security plan. France announced this week it was moving its aircraft carrier strike group into the Red Sea in preparation.

Britain and France have led meetings involving several dozen countries on a coalition to reestablish freedom of navigation in the strait. But they stress it won’t start until there is a sustainable ceasefire and the maritime industry is reassured ships can go through the strait safely.

Diplomacy continues ‘day and night’

U.S. President Donald Trump has insisted the ceasefire is holding but has reiterated threats to resume full-scale bombing if Iran doesn’t accept an agreement to reopen the strait and roll back its nuclear program.

On Friday, Iranian foreign ministry spokesperson Esmail Baghaei said the country was not paying attention to “deadlines,” according to state-run IRNA.

Also on Friday, a top Iranian official said Supreme Leader Mojtaba Khamenei was in “complete health” and eventually would appear in public. Khamenei hasn’t been seen or heard in public since the war began, fueling speculation about his status.

Mazaher Hosseini, affiliated with the office of Iran’s former Supreme Leader, made the comment at a pro-government gathering. Hosseini said Mojtaba had suffered knee and back injuries in the war's opening attacks but they’ve largely healed.

Diplomacy continues. Pakistani Prime Minister Shehbaz Sharif said his country has been in contact with the U.S. and Iran “day and night” in an effort to extend the ceasefire and reach a peace deal.

Russia’s foreign ministry said Saturday that it, as well as Saudi Arabia, was calling for diplomatic efforts to reach a “sustainable, long-term agreement” to end the war.

Egyptian and Qatari top diplomats reiterated that diplomacy is the sole path to a solution, according to a readout of a Saturday phone call between the foreign ministers of Egypt and Qatar.

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Magdy reported from Cairo. Associated Press writer Jill Lawless contributed from London.